Preheat your oven to 350°F (175°C). Prepare a 9-inch springform pan by lining with parchment paper and spraying the sides with non-stick spray.

In a mixing bowl, combine the flour, baking powder, salt, light brown sugar, and granulated sugar. Cut in the cold butter until the mixture resembles coarse crumbs. Optional: add lemon zest.

Add the eggs and vanilla extract to the crumb mixture, stirring gently until it holds together. Reserve one-third for topping, press the rest into the springform pan.

In another bowl, beat together the mascarpone and cream cheese until smooth. Mix in the caster sugar, vanilla extract, and corn starch without lumps. Add eggs carefully.

Pour half of the cheesecake mixture into the crust layer, spread evenly and add half the blueberries. Top with the rest of the mixture, remaining blueberries, and reserved crumbs.

Bake for 65 to 75 minutes until golden and a toothpick inserted comes out slightly clean. Avoid overbaking.

Let the cake cool in the pan for 30 minutes. Whisk powdered sugar with milk to create a glaze. Drizzle over cooled cake before serving.