Pie with streusel on a baking sheet

Ingredients:

Streusel

• 1.5 cups dark brown sugar
• 2/3 cup granulated sugar
• 1 tbsp. ground cinnamon
• 1 teaspoon coarse salt
• 220 g (1 cup) unsalted butter, melted
• 3 cups premium flour

Pie

• Cooking spray to spray the baking sheet
• 3 cups premium flour
• 1 and 3/4 teaspoons baking powder
• 3/4 tsp baking soda
• 1 teaspoon coarse salt
• 165 g unsalted butter at room temperature
• 1 and 3/4 cups granulated sugar
• 3 large eggs
• 1 tbsp vanilla extract
• 1 and 1/4 cups sour cream

Preparation:

1. Streusel:
   
   Combine brown sugar, granulated sugar, cinnamon, and salt in a medium bowl. Drizzle with melted butter and mix with a fork until smooth. Add flour and mix with a fork until medium-sized lumps form. Don't overmix, or the mixture will turn into a paste.
2. Preheat oven to 350°F (175°C) and spray a 18 x 13-inch baking pan with cooking spray.
3. Pie:
   
   In a medium bowl, combine 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 5 minutes. Add the eggs one at a time, beating well after each addition. Add the vanilla extract. Beat until combined.
4. Reduce mixer speed to low and add the flour mixture in three additions, alternating with two additions of sour cream, beginning and ending with the flour. Knead until smooth.
5. Place the batter (it will be very thick) on the prepared baking sheet and smooth the surface with a spatula. Sprinkle with streusel and gently press it into the batter to adhere the crumbs.
6. Bake until the streusel is golden brown and a toothpick inserted into the center comes out clean, 40-45 minutes. Let cool completely on the baking sheet, about 1 hour. Slice and serve.