01 - Preheat the oven to 350°F. Grease and flour a 9-inch round springform pan or an 8x8-inch baking dish.
02 - In a medium bowl, combine flour, granulated sugar, brown sugar, salt, cinnamon, melted butter, and lemon zest. Mix with a fork until crumbly. Set aside.
03 - In a separate bowl, whisk together flour, baking powder, baking soda, and salt for the cake base.
04 - In a large mixing bowl, cream the butter and sugar until light and fluffy, about 2-3 minutes. Beat in eggs one at a time.
05 - Mix in sour cream, milk, lemon zest, lemon juice, and vanilla extract until well combined.
06 - Gradually add the dry ingredients to the wet mixture, mixing just until combined. Do not overmix.
07 - Gently fold in the blueberries with a spatula, being careful not to crush them.
08 - Spread the batter evenly into the prepared pan. Sprinkle the crumble topping evenly over the batter.
09 - Bake for 40-45 minutes, or until a toothpick inserted in the center comes out clean and the top is golden brown.
10 - Cool the cake in the pan for 15 minutes, then remove and transfer to a wire rack to cool completely. Optionally, whisk powdered sugar and lemon juice to form a glaze and drizzle over cooled cake.