Assorted berry pie with coffee

Ingredients:

Streusel

• 3/4 cup flour
• 2/3 cup firmly packed light brown sugar
• 0.5 cups oatmeal
• 1 teaspoon ground cinnamon
• A pinch of fine salt
• 5 tablespoons unsalted butter, room temperature

Pie

• 110g unsalted butter, room temperature, plus extra for greasing the pan
• 2 cups premium flour
• 1 teaspoon baking powder
• 0.5 tsp of soda
• 0.5 tsp fine salt
• 1 cup granulated sugar
• 2 large eggs
• 2 tsp vanilla extract
• 1 cup sour cream
• 2 cups frozen berry mixture, thawed

Preparation:

1. In a small bowl, combine the flour, brown sugar, oats, cinnamon, and salt. Add the butter and mix thoroughly with your fingers or a fork until all the butter is evenly distributed and incorporated into the flour. Use your fingers to form small to medium sized clumps.
2. Preheat oven to 175°C. Grease a 20cm square baking pan with butter.
3. Pie:
   
   In a small bowl, whisk together the flour, baking powder, baking soda, and salt. In a large bowl, beat the butter and sugar with a mixer on medium-high speed until light and fluffy, about 3 minutes. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract. Reduce the mixer speed to low and add the flour mixture in 3 additions, alternating with the sour cream, beginning and ending with the flour. Mix just until all ingredients are incorporated.
4. Spoon half the batter (it will be very thick) into the prepared pan and smooth the surface with a spatula. Sprinkle with berries. Top with the remaining batter and smooth the surface. Sprinkle with streusel.
5. Bake until the crust is deep golden brown and a toothpick inserted into the center comes out clean, about 1 hour. Let cool in the pan for 20 minutes, then invert the cake onto a plate; invert it back onto a wire rack to cool completely.