Brown Butter Raspberry Oatmeal Jam Squares

Why You’ll Love This Recipe

• Deep, nutty flavor from real brown butter in both the base and crumble.
• Generous, jammy raspberry layer that bakes thick and shiny—not runny.
• Beautiful texture contrast: crisp golden top, tender oat base.
• Simple pantry ingredients; no mixer required.

Grocery List

• Produce: 1 lemon; optional fresh raspberries (3/4 cup / 90 g)
• Dairy: Unsalted butter (12 tbsp / 170 g)
• Pantry: Old-fashioned rolled oats, all-purpose flour, light brown sugar, granulated sugar, raspberry jam (about 400 g), vanilla extract, ground cinnamon, baking powder, kosher salt, cornstarch, optional chopped nuts, optional coarse sugar

Full Ingredients

Oat Base + Crumble

• 12 tbsp (170 g) unsalted butter
• 1 1/2 cups (150 g) old-fashioned rolled oats
• 1 1/4 cups (160 g) all-purpose flour
• 3/4 cup (150 g) packed light brown sugar
• 1/4 cup (50 g) granulated sugar
• 1/2 tsp baking powder
• 3/4 tsp kosher salt (use 1/2 tsp if using fine salt)
• 1/2 tsp ground cinnamon (optional)
• 2 tsp vanilla extract
• Optional: 1/2 cup (55 g) chopped toasted almonds or pecans (fold into crumble topping)
• Optional: 1 tbsp coarse sugar for sprinkling

Raspberry Layer

• 1 1/4 cups (about 400 g) raspberry jam or preserves, seedless preferred
• 1 tbsp (15 ml) fresh lemon juice
• 2 tsp (6 g) cornstarch
• Optional: 3/4 cup (90 g) fresh or frozen raspberries, lightly mashed
• Pinch of salt

Step-by-Step Instructions

Step 1: Prep the pan and oven

Heat the oven to 350°F (175°C) with a rack in the center. Line an 8-inch (20 cm) square metal baking pan with a parchment sling, leaving overhang on two sides for easy lifting. Lightly grease the parchment and the exposed sides of the pan.

Step 2: Brown the butter

In a light-colored saucepan over medium heat, melt the butter. Continue cooking, stirring and swirling, until the foam subsides and the milk solids turn deep golden brown and smell nutty, 5–7 minutes. Immediately scrape all the butter and browned bits into a heatproof bowl to stop the cooking. Cool 5–10 minutes until warm but still fluid.

Step 3: Make the oat crumble

In a large bowl, whisk the oats, flour, brown sugar, granulated sugar, baking powder, salt, and cinnamon (if using). Pour in the warm brown butter and vanilla. Stir with a fork until the mixture turns into evenly moistened, clumpy crumbs that hold together when squeezed. Reserve 1 1/2 cups of the mixture for the topping; set aside.

Step 4: Press and par-bake the base

Tip the remaining crumb mixture into the prepared pan. Press it firmly and evenly into a compact layer using the bottom of a measuring cup. Bake until set and just turning pale golden at the edges, 10–12 minutes. Leave the oven on.

Step 5: Stir the raspberry filling

While the base bakes, in a bowl stir the jam with lemon juice, cornstarch, and a pinch of salt until smooth. If using fresh or frozen raspberries, fold them in gently—they add bright flavor and extra body. The cornstarch helps the layer slice cleanly.

Step 6: Assemble and bake

Spread the raspberry mixture evenly over the warm crust, right to the edges. Sprinkle the reserved crumble over the top in small clumps, leaving some raspberry peeking through. If you like, scatter on the chopped nuts and sprinkle with coarse sugar. Bake until the top is deeply golden and the filling is bubbling at the edges, 20–24 minutes.

Step 7: Cool and cut

Cool the pan on a rack for 1 hour, then chill 30 minutes for the neatest slices. Lift out using the parchment overhang. Cut into 16 squares with a sharp knife, wiping the blade between cuts. Serve slightly warm or at room temperature.

Pro Tips

• Brown butter cues: look for amber color and toasty, milk-solid specks; remove from heat promptly to avoid burnt bitterness.
• Pack the base firmly so it stays crisp beneath the jam. A flat-bottomed measuring cup works best.
• Par-baking the crust keeps the bottom from going soggy under the thick raspberry layer.
• For tidy edges, cool completely and chill briefly before slicing; warm the knife under hot water and wipe dry between cuts.
• Use seedless jam for clean layers, or keep seeds for rustic texture—both bake beautifully.

Variations

• Blueberry–lemon: swap raspberry jam for blueberry jam; add 1 tsp lemon zest to the crumble.
• Almond crunch: mix 1/2 cup (55 g) sliced almonds into the topping and add 1/4 tsp almond extract to the crumble.
• Gluten-free: use a 1:1 gluten-free baking flour and certified gluten-free rolled oats.

Storage & Make-Ahead

Store squares airtight at room temperature up to 3 days or refrigerate up to 1 week. Freeze well-wrapped for 2–3 months; thaw at room temperature. To refresh the crumble, warm individual squares in a 300°F (150°C) oven for 5–8 minutes.

Nutrition (per serving)

Approximate values for 1 of 16 squares (without optional nuts/coarse sugar): 265 calories; 12 g fat; 41 g carbohydrates; 3 g protein; 1 g fiber; 120 mg sodium. Values vary by jam brand and portion size.