In a medium-sized mixing bowl, whisk together the sugars, cake flour, graham cracker crumbs, cinnamon, nutmeg, and salt. Pour in the melted butter and stir with a spatula until a thick crumble forms. Allow to sit while preparing the remainder of the cake.
To Make the Cheesecake Layer
In a medium-sized mixing bowl, beat together the cream cheese, sugar, and vanilla extract. Add the egg and beat until smooth.
To Make the Cake
Preheat the oven to 325°F (165°C). Spray an 8-inch or 9-inch square baking dish or round springform pan with baking spray; set aside.
In the bowl of a stand mixer, mix the flour, sugar, baking soda, and salt on low. Gradually add the butter one tablespoon at a time while mixing on low. Continue mixing until crumbs form, about 2 minutes. Add the egg and yolk, then mix. Add the lemon zest, vanilla, and buttermilk, and beat on medium-high speed until light and fluffy, about 1-2 minutes, scraping the bottom of the bowl halfway through.
Pour the cake batter into the prepared pan, spreading it into an even layer. Pour the cheesecake layer on top, spreading evenly. Cover with blueberries, then sprinkle with the crumb mixture, breaking it into smaller pieces as needed.
Place in the oven and bake for 35-45 minutes, or until a cake tester inserted into the center comes out clean, and the center of the cake just barely jiggles. (Note that baking time will vary depending on the type and size of the pan you use.) Remove from the oven and allow to cool in the pan for at least 30 minutes before slicing and serving.
Notes
*9 oz. of blueberries is approximately one and a half of Driscoll's standard-size blueberry cartons. -You could easily interchange the blueberries with ripe peaches, strawberries, blackberries, or raspberries... or use a combination!To STORE your Blueberry Crumble Cake, refrigerate it in an airtight container for up to 4-5 days.For longer storage, wrap the cake tightly in plastic wrap, followed by aluminum foil, and FREEZE it for up to 2 months. Thaw in the fridge overnight before serving.