Peanut Butter and Jam Crumble Bars with Brown Butter

Why You’ll Love This Recipe

• Classic peanut butter and strawberry jam flavors in a bakery-style bar with layers and crunch.
• Brown-butter oat crust adds deep, nutty aroma without extra effort.
• Pantry-friendly and forgiving: use your favorite jam and common baking staples.
• Perfect for make-ahead snacking, bake sales, and lunchbox treats.

Grocery List

• Produce: 1 lemon
• Dairy: Unsalted butter
• Pantry: Old-fashioned rolled oats, all-purpose flour, light brown sugar, thick strawberry jam, creamy no-stir peanut butter, roasted salted peanuts, vanilla extract, baking powder, fine sea salt, flaky sea salt, cornstarch (optional), ground cinnamon (optional)

Full Ingredients

Oat Brown-Butter Base

• 8 tbsp (from browned butter; approx 113 g by volume) browned unsalted butter, warm
• 1 cup (100 g) old-fashioned rolled oats
• 1 cup (130 g) all-purpose flour
• 1/3 cup (70 g) light brown sugar, packed
• 1/4 tsp baking powder
• 1/2 tsp fine sea salt
• 1 tsp vanilla extract

Strawberry Layer

• 1 1/4 cups (400 g) thick strawberry jam
• 1 tbsp fresh lemon juice
• 1 tsp cornstarch (optional, if jam is thin)

Peanutty Streusel

• 4 tbsp (from browned butter; approx 57 g by volume) browned unsalted butter, slightly cooled
• 1/2 cup (135 g) creamy no-stir peanut butter
• 1/3 cup (65 g) light brown sugar, packed
• 1/2 cup (64 g) all-purpose flour
• 2/3 cup (65 g) old-fashioned rolled oats
• 1/4 tsp fine sea salt
• 1/2 tsp vanilla extract
• 1/3 cup (45 g) roasted salted peanuts, chopped
• Pinch ground cinnamon (optional)

Finish

• 1/2 tsp flaky sea salt (or to taste)

Step-by-Step Instructions

Step 1: Prep the pan and brown the butter

Preheat the oven to 350°F (175°C). Line an 8-inch (20 cm) square baking pan with parchment, leaving an overhang on two sides for easy lifting. In a light-colored saucepan, melt 12 tbsp (170 g) unsalted butter over medium heat. Continue cooking, stirring and swirling often, until the milk solids turn golden brown and smell nutty, 5–7 minutes. Immediately scrape the browned butter and toasty bits into a heatproof bowl. You’ll have roughly 10 tbsp after moisture evaporates; divide about 8 tbsp for the base and 4 tbsp for the streusel.

Step 2: Make the oat brown-butter base

In a mixing bowl, combine oats, flour, brown sugar, baking powder, and fine salt. Drizzle in 8 tbsp warm browned butter and the vanilla. Stir until the mixture looks like damp sand and holds together when pressed. Tip into the prepared pan and press firmly and evenly into a compact layer, getting into the corners.

Step 3: Par-bake the crust

Bake the crust for 12–14 minutes, until lightly golden at the edges and set on top. If any spots puff, press gently with the back of a spoon. Set the pan on a rack while you prepare the filling.

Step 4: Prepare the strawberry layer

In a small bowl, stir the jam with the lemon juice. If your jam is on the thin side, whisk in the cornstarch and warm the mixture in a small saucepan over low heat just until glossy and slightly thickened (1–2 minutes), then cool 2–3 minutes. Spread the jam evenly over the warm crust, leaving a tiny margin at the edges.

Step 5: Mix the peanutty streusel

In a bowl, stir peanut butter with the reserved 4 tbsp browned butter and vanilla until smooth. Add brown sugar, flour, oats, fine salt, and cinnamon if using. Toss in the chopped peanuts. Use your fingers to squeeze the mixture into clumps ranging from pea- to marble-size.

Step 6: Assemble and bake

Scatter the streusel evenly over the jam, leaving some bits of jam peeking through. Bake 22–26 minutes, until the topping is golden and the jam bubbles at the edges. Remove from the oven and immediately sprinkle with flaky sea salt.

Step 7: Cool and slice

Cool the pan on a rack until room temperature, about 2 hours. For the cleanest cuts, chill an additional 30 minutes. Use the parchment sling to lift the slab out. Slice into 16 bars, wiping the knife between cuts.

Pro Tips

• Use a light-colored pot to brown butter so you can see the milk solids turn golden rather than burn.
• If your jam is runny, do not skip the quick stovetop thicken—it keeps layers distinct and bars tidy.
• Press the base firmly; a compact crust prevents crumbling when you slice.
• Clump the streusel with your fingers for varied texture—some fine crumbs, some larger nuggets.
• Sprinkle flaky salt while the bars are hot so the crystals hug the surface without dissolving completely.

Variations

• Swap the jam: Raspberry, blackberry, or mixed-berry jam all work beautifully. Add 1 tsp lemon zest for brightness.
• Chocolate twist: Fold 1/2 cup (85 g) chopped dark chocolate into the streusel or drizzle melted chocolate over cooled bars.
• Gluten-free: Use certified GF oats and a cup-for-cup gluten-free flour blend.

Storage & Make-Ahead

Store bars airtight at room temperature for up to 3 days, or refrigerate up to 1 week. For longer storage, freeze individually wrapped bars in a freezer bag for up to 2 months; thaw at room temperature 30–45 minutes. The crust can be par-baked and cooled a day ahead; assemble with jam and streusel and bake when ready.

Nutrition (per serving)

Approximate per bar: 350 calories; 17 g fat; 45 g carbohydrates; 6 g protein; 3 g fiber; 23 g sugars; 160 mg sodium. Values will vary based on jam and peanut butter brands.