Quick Recipe Version (TL;DR)

Yield: 8 servings (one 9-inch pie)
Prep Time: 30 minutes
Cook Time: 35 minutes
Total Time: 4 hours (includes cooling and chilling)

Quick Ingredients

1 1/2 cups (150 g) chocolate cookie crumbs
6 Tbsp (85 g) unsalted butter, melted
2 Tbsp (25 g) granulated sugar + pinch salt (for crust)
6 oz (170 g) bittersweet chocolate, finely chopped
2 Tbsp (14 g) unsweetened cocoa powder
2 Tbsp (28 g) unsalted butter
4 large eggs, separated (room temperature)
3/4 cup (150 g) granulated sugar, divided
1/2 cup (120 ml) heavy cream
2 tsp vanilla extract
1/4 tsp fine salt
1/4 tsp cream of tartar or 1 tsp lemon juice
1 cup (240 ml) heavy cream + 2 Tbsp powdered sugar (topping, optional)

Do This

1. Heat oven to 350°F (175°C). Mix cookie crumbs, sugar, salt, and melted butter; press into a 9-inch pie plate. Bake 10 minutes, then cool slightly. Reduce oven to 325°F (165°C).
2. Melt chopped chocolate, cocoa, and butter together gently until smooth. Let cool to warm.
3. Whisk egg yolks with 1/2 cup (100 g) sugar until thick and pale, then whisk in warm chocolate mixture, heavy cream, vanilla, and salt.
4. Beat egg whites with cream of tartar to soft peaks, then slowly add remaining 1/4 cup (50 g) sugar and whip to glossy medium-firm peaks.
5. Fold egg whites into chocolate base in 3 additions until no streaks remain. Pour into crust and smooth the top.
6. Bake at 325°F (165°C) for 23–28 minutes, until puffed at edges with a soft jiggle in the center. Cool to room temperature, then chill at least 2 hours. Top with lightly sweetened whipped cream before serving.

Why You’ll Love This Recipe

Silky and airy: a baked chocolate custard that eats like a mousse, with a tender, soufflé-like crumb.
Deep chocolate flavor: a double hit of real chocolate and cocoa in a crunchy cookie crust.
Make-ahead friendly: the pie must be chilled, so it is perfect for preparing the day before.
Elegant but approachable: impressive enough for guests, simple enough for a relaxed weekend bake.

Grocery List

Produce: Fresh berries for garnish (optional), fresh mint (optional)
Dairy: Unsalted butter, heavy cream, large eggs
Pantry: Chocolate wafer cookies or chocolate graham crackers, granulated sugar, powdered sugar, unsweetened cocoa powder, bittersweet chocolate (60–70% cacao), vanilla extract, fine salt, cream of tartar or lemon juice

Full Ingredients

Chocolate Cookie Crust

1 1/2 cups (150 g) finely crushed chocolate wafer cookies or chocolate graham crackers
2 Tbsp (25 g) granulated sugar
Pinch fine salt
6 Tbsp (85 g) unsalted butter, melted

Baked Chocolate Mousse Filling

6 oz (170 g) bittersweet or semisweet chocolate (60–70% cacao), finely chopped
2 Tbsp (14 g) unsweetened cocoa powder, sifted
2 Tbsp (28 g) unsalted butter
4 large eggs, separated, at room temperature
3/4 cup (150 g) granulated sugar, divided
1/2 cup (120 ml) heavy cream, at room temperature
2 tsp vanilla extract
1/4 tsp fine salt
1/4 tsp cream of tartar or 1 tsp fresh lemon juice (to stabilize the egg whites)
Optional: 1 Tbsp coffee liqueur or strong cooled espresso for extra depth

For Serving (Optional but Recommended)

1 cup (240 ml) heavy cream, cold
2 Tbsp (15 g) powdered sugar
1/2 tsp vanilla extract
Chocolate curls or shavings
Fresh berries and/or small mint sprigs

Step-by-Step Instructions

Step 1: Prepare the pan and preheat the oven

Position a rack in the center of your oven. Preheat to 350°F (175°C). Lightly grease a 9-inch (23 cm) deep-dish pie plate with a thin smear of butter or nonstick spray. This helps the crumb crust release cleanly when you slice the pie.

Have all your filling ingredients measured and the eggs separated before you start making the mousse; the process moves quickly once the chocolate is melted.

Step 2: Make and prebake the cookie crust

In a medium bowl, stir together the chocolate cookie crumbs, 2 Tbsp (25 g) sugar, and a pinch of salt. Pour in the melted butter and mix with a fork until all the crumbs are evenly moistened and resemble wet sand.

Transfer the mixture to the prepared pie plate. Press the crumbs firmly and evenly across the bottom and up the sides, using the bottom of a measuring cup or glass to compress the crust so it is compact and smooth.

Bake at 350°F (175°C) for 8–10 minutes, until fragrant and just starting to look dry at the edges. Remove from the oven, place on a wire rack, and reduce the oven temperature to 325°F (165°C). Let the crust cool while you prepare the filling.

Step 3: Melt the chocolate for the mousse

Place the chopped chocolate, cocoa powder, and 2 Tbsp (28 g) butter in a heatproof bowl. Set the bowl over a saucepan of barely simmering water (the bottom of the bowl should not touch the water), creating a gentle double boiler.

Stir frequently until the chocolate and butter are mostly melted and smooth. Remove the bowl from the heat and continue stirring until completely silky with no lumps. The mixture should be warm but not hot. If using, stir in the coffee liqueur or strong espresso. Set aside to cool slightly while you start the custard base.

Alternatively, melt in the microwave in 20–30 second bursts, stirring well between each burst, until smooth. Be careful not to overheat.

Step 4: Make the chocolate custard base

In a medium mixing bowl, whisk the egg yolks with 1/2 cup (100 g) of the granulated sugar until the mixture is thick, pale, and falls from the whisk in ribbons, 1–2 minutes by hand or about 1 minute with a hand mixer on medium-high.

Slowly whisk the warm (not hot) melted chocolate mixture into the yolks, pouring in a thin stream while whisking constantly. Once incorporated, whisk in the 1/2 cup (120 ml) heavy cream, vanilla extract, and 1/4 tsp salt until smooth and glossy. The mixture will be fairly thick; set it aside while you whip the egg whites.

Step 5: Whip and fold in the egg whites

In a clean, dry bowl (any fat or yolk will prevent them from whipping), add the room-temperature egg whites. Beat on medium speed until foamy. Sprinkle in the cream of tartar or lemon juice and continue beating until soft peaks form.

Gradually add the remaining 1/4 cup (50 g) granulated sugar, 1–2 Tbsp at a time, while beating on medium-high speed. Continue whipping until the egg whites are glossy and form medium-firm peaks that hold their shape but still have a slightly soft tip when the beaters are lifted.

To combine, use a large rubber spatula to fold about one-third of the whipped whites into the chocolate base, using broad, gentle strokes. This first addition can be mixed a bit more vigorously to lighten the batter. Fold in the remaining whites in two more additions, taking care not to deflate the mixture. Stop as soon as no large streaks of white remain.

Step 6: Fill the crust and bake the mousse pie

Pour the airy chocolate filling into the cooled prebaked crust. Smooth the top with an offset spatula or the back of a spoon. If you like, gently tap the pie plate once or twice on the counter to release any large air pockets (do not overdo this, or you will lose volume).

Place the pie on a baking sheet for easier handling and to catch any drips. Bake at 325°F (165°C) for 23–28 minutes. The pie is done when the edges are puffed, the top looks dry and slightly cracked in places, and the center still has a soft, gentle jiggle when you nudge the pan. Do not bake until fully firm or it will be dry instead of silky.

Remove the pie to a wire rack. As it cools, it will deflate slightly and the top will settle into a smooth, delicate surface—that is exactly what you want for a mousse-like texture.

Step 7: Cool, chill, and garnish

Let the pie cool completely at room temperature, about 1–1 1/2 hours. Once cool, cover loosely (avoid touching the surface with plastic wrap) and refrigerate for at least 2 hours, or up to 24 hours. Chilling allows the custard to fully set into a silky, sliceable, airy mousse.

Just before serving, make the whipped cream topping: in a chilled bowl, beat 1 cup (240 ml) cold heavy cream with 2 Tbsp (15 g) powdered sugar and 1/2 tsp vanilla extract until soft to medium peaks form. Spread or pipe the whipped cream over the chilled pie, or dollop each slice with a generous spoonful.

Finish with chocolate curls or shavings and a few fresh berries or mint leaves, if desired. Slice with a sharp, thin knife wiped clean between cuts for the cleanest layers.

Pro Tips

Use good chocolate: Because the filling is mostly chocolate, choose a bar you enjoy eating plain, around 60–70% cacao for a balanced flavor.
Room-temperature eggs whip best: Separate the eggs while cold (easier), then let the whites sit out 20–30 minutes before whipping.
Do not overbake: Pull the pie out while the center still has a soft wobble. It will continue to set as it cools and chills, giving you a custardy, mousse-like texture.
Protect the crust: If your crust edges start to look too dark during baking, loosely shield them with a ring of foil.
Clean slices: Dip your knife in hot water and wipe it dry between cuts to keep the layers neat and the crust intact.

Variations

Mocha mousse pie: Replace 2 Tbsp of the heavy cream in the filling with 2 Tbsp strong espresso, and add 1 tsp instant espresso powder along with the cocoa.
Orange-chocolate version: Add 1–2 tsp finely grated orange zest to the chocolate custard base and 1 Tbsp orange liqueur in place of coffee liqueur.
Salted caramel swirl: Before baking, drizzle 1/4 cup (60 ml) slightly warmed thick caramel sauce over the chocolate filling and gently marble it with a skewer. Sprinkle with a few flakes of sea salt just before serving.

Storage & Make-Ahead

The pie keeps very well and is ideal for making ahead. Once completely cool, cover the pie and refrigerate for up to 3 days before serving. For the best texture, add the whipped cream topping and garnishes on the day you plan to serve it, ideally within a few hours of presenting.

Leftover slices can be stored, covered, in the refrigerator for up to 3 days. The crust will gradually soften but the flavor remains excellent. This pie does not freeze well because the custard and whipped egg whites can weep and become grainy upon thawing.

Nutrition (per serving)

Approximate values per serving (1/8 of the pie, without optional garnishes): about 520 calories, 38 g fat, 22 g saturated fat, 48 g carbohydrates, 4 g fiber, 33 g sugar, 7 g protein, and 260 mg sodium. Values will vary based on specific ingredients and portion sizes.

Light Baked Chocolate Mousse Pie with Cookie Crust