Preparation

• Preheat the oven to 350°F. Spray a 9x13 baking dish with baking spray, set aside. In a medium-sized bowl whisk together the flour, baking powder, baking soda, and salt, set aside.
• In a large bowl, whisk together the sugar, butter, vanilla, and eggs until smooth.
• Add half of the flour to the wet mixture and stir it in until there are no more dry patches.
• Stir in half of the sour cream until there are no more streaks of white. Repeat with the remaining flour and sour cream.
• Fold in the blueberries and lemon zest, set aside.
• In a large bowl, whisk together the sugar, flour, and lemon zest. Add the butter to the bowl and cut it in with a pastry cutter or rub the butter pieces with the flour through your fingers until the mixture resembles wet sand with a few larger chunks the size of peas mixed in.
• Add half of the cake batter to the bottom of the baking dish and smooth it out.
• Add half of the crumble mixture evenly.
• Spread out the remaining cake batter on top.
• Sprinkle the remaining crumble on top.
• Bake for 55-65 minutes until a toothpick inserted into the center comes out clean. Let cool on a wire rack.
• While the cake is cooling, make the glaze by whisking together the powdered sugar, lemon juice, and vanilla until smooth.
• Serve the cake warm or room temperature with a drizzle of the glaze for serving.