Preheat your oven to 300℉ and spread the all-purpose flour on a baking sheet. Bake the flour for 8 minutes to heat-treat it, ensuring your edible cookie dough is safe to eat. In a mixing bowl, beat the softened unsalted butter and white sugar until pale and fluffy. Add in pure vanilla extract and milk, mixing until smooth. Gradually incorporate the heat-treated flour, salt, and festive Christmas sprinkles, forming the dough into 15 discs. Then, place them in the freezer while you prepare the cake batter.

Increase the oven temperature to 350℉ and prepare three 8-inch cake pans by greasing and lining them with parchment paper. In a large bowl, sift together the remaining flour, baking powder, baking soda, and salt. In another bowl, beat softened butter, oil, and white sugar together until light and fluffy. Add in pure vanilla extract, room temperature eggs, and sour cream, mixing until well combined. Finally, fold in the dry ingredient mixture along with buttermilk, mixing until just combined into a smooth batter.

Evenly divide the cake batter among the prepared pans, smoothing the tops for an even bake. Lay the frozen cookie dough discs in layers within the batter, ensuring they’re spaced out. Place the pans in the preheated oven and bake for 26-32 minutes. Check for doneness by inserting a toothpick into the center; it should come out clean. Once baked, let the cake layers cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

While the cake layers are cooling, make the luscious cream cheese frosting. In a mixing bowl, beat softened unsalted butter until it’s fluffy, then add in softened cream cheese and continue mixing until smooth. Gradually mix in sifted powdered sugar until well incorporated, then add a splash of vanilla extract and a pinch of salt. Beat until the frosting reaches a creamy, spreadable texture.

Once the cake layers are cool, level them if necessary. Spread a layer of frosting between each cake layer alongside a little extra edible cookie dough for added flavor. Apply a thin crumb coat of frosting over the entire cake to trap any loose crumbs, then place the cake in the freezer for 15 minutes. After chilling, cover the cake with a thicker layer of frosting for a smooth finish, and decorate with additional cookie dough balls and sprinkles for a festive touch.