• Preheat oven to 350°F (175°C). Line a 9-inch springform pan with parchment paper and spray with nonstick cooking spray.
• Mix flour, baking powder, salt, sugars, and lemon zest. Add cubed butter and mix until crumbly. Add eggs and vanilla. Press ⅔ of the mixture into the pan. Chill.
• Beat mascarpone, cream cheese, sugar, corn starch, eggs, and vanilla until combined. Pour half into the crust, scatter ⅔ cup blueberries, then add the rest of the filling. Top with blueberries and remaining crumbs.
• Bake for 65-75 minutes or until golden. Tent with foil if needed.
• Mix powdered sugar and milk until smooth. Drizzle over the cooled cake.