Preheat your oven to 175ºC (350ºF) and prepare a 9-inch springform pan with parchment paper and greased sides.

In a bowl, mix all-purpose flour, granulated sugar, dark brown sugar, cinnamon, and cold butter until crumbly.

In a large bowl, cream the room-temperature butter, granulated and brown sugars until light and fluffy, about 3-4 minutes. Add eggs one at a time.

Gradually mix in half of the sifted all-purpose flour with baking powder and salt, then add the rest along with lemon zest, sour cream, vegetable oil, and vanilla.

Toss blueberries with cornstarch, then fold half into the batter and pour into the prepared pan, topping with the remaining blueberries and crumble.

Bake for 45-50 minutes, checking doneness with a toothpick at 45 minutes. Let cool in the pan for 10 minutes before transferring to a wire rack.

For the lemon glaze, whisk together powdered sugar, lemon juice, vanilla extract, and sour cream until smooth, then drizzle over the cooled cake.