Raspberry Oat Bar Recipe

Preheat and prepare pan

Preheat oven to 350°F (175°C). Line a 9x9-inch (23x23 cm) square baking pan with parchment paper leaving an overhang for easy removal; lightly grease the parchment.

Combine dry ingredients

In a large bowl, whisk together 2 cups rolled oats, 1 cup all-purpose flour, 3/4 cup packed light brown sugar, 2 tbsp granulated sugar, 1/2 tsp baking powder, and 1/2 tsp salt until evenly mixed.

Cut in butter

Cut 12 tbsp (1.5 sticks) cold unsalted butter into 1/2-inch cubes and add to the oat-flour mixture. Using a pastry cutter, two forks, or your fingertips, cut the butter into the dry mix until the mixture resembles coarse crumbs with some pea-sized butter pieces (a few larger clumps will give a nice texture). Stir in 1 tsp vanilla extract.

Form crust

Reserve about 1 1/2 cups of the oat mixture for the topping. Press the remaining oat mixture evenly and firmly into the prepared 9x9 pan to form the crust (use the bottom of a measuring cup for even compaction). Bake the crust for 12-14 minutes, until it is lightly golden at the edges but not fully browned. Remove from oven and set aside.

Make raspberry jam filling

While the crust bakes, combine 3 cups raspberries and 1/2 cup granulated sugar in a medium saucepan over medium heat. Cook, stirring occasionally, until the raspberries release their juices and begin to simmer, about 5 minutes.

Thicken filling

In a small bowl, whisk 2 tsp cornstarch with 1 tbsp water to make a slurry. Stir the slurry into the simmering raspberries along with 1 tbsp lemon juice. Continue to cook and stir for 2–3 minutes until the mixture thickens to a jam-like consistency. Remove from heat and let cool 5–10 minutes so it is warm but not piping hot (this prevents the crust from getting soggy). If you prefer a smoother filling, press the cooked mixture through a coarse sieve to remove seeds, then cool slightly.

Assemble filling on crust

Spread the cooled raspberry filling evenly over the partially baked crust using an offset spatula or the back of a spoon, leaving a small border at the edges.

Top and bake

Crumble the reserved oat mixture evenly over the raspberry layer, breaking up any large clumps so the topping covers the jam. Optionally sprinkle 1/8 tsp sea salt over the top to balance sweetness. Bake in the preheated 350°F (175°C) oven for 20–25 minutes, until the topping is golden brown and the filling is bubbling at the edges.

Cool and slice

Remove the pan from the oven and let the bars cool completely in the pan on a wire rack (2 hours recommended) so the filling sets. Use the parchment overhang to lift the bars from the pan and transfer to a cutting board. Dust the top with 2 tbsp powdered sugar, if using, and cut into 9 or 12 bars.

Storage

Store bars in an airtight container at room temperature for up to 2 days, or refrigerate for up to 5 days. For longer storage, freeze individually wrapped bars for up to 3 months and thaw at room temperature.