# What You'll Need:
→ Filling
01 - 4 cups mixed fresh berries (blueberries, raspberries, strawberries, blackberries)
02 - 1/2 cup granulated sugar
03 - 2 tablespoons all-purpose flour
04 - 1 tablespoon lemon juice
→ Topping
05 - 3/4 cup rolled oats
06 - 1/2 cup all-purpose flour
07 - 1/2 cup packed brown sugar
08 - 1/2 teaspoon ground cinnamon
09 - 1/4 teaspoon salt
10 - 6 tablespoons unsalted butter, cold and cut into small pieces
# Step-by-Step:
01 - Combine mixed berries, granulated sugar, all-purpose flour, and lemon juice in a large bowl. Gently toss to coat berries evenly.
02 - Spread the berry mixture evenly in a greased 8-inch square or similar size baking dish.
03 - In a separate bowl, whisk together rolled oats, all-purpose flour, brown sugar, ground cinnamon, and salt. Add cold butter pieces and cut in with a pastry blender or forks until the mixture resembles coarse crumbs.
04 - Spoon and gently spread the oat streusel evenly over the berry filling.
05 - Bake in a preheated oven at 350°F for 40 minutes or until the berries are bubbling and the topping is golden brown.
06 - Allow to cool for 15 minutes before serving to set the filling. Serve warm or at room temperature.