1-Preheat your oven: Preheat your oven to 350°F (175°C). Grease two 8-inch cake pans thoroughly and dust with flour, lining the bottoms with parchment paper for easy removal.

2-Mix wet ingredients: In a large mixing bowl, beat together the granulated sugar, vegetable oil, melted unsalted butter, large eggs, egg yolks, and pure vanilla extract until the mixture is light in color.

3-Add sour cream: Add the sour cream (or plain Greek yogurt) to the mixture and beat until combined.

4-Combine dry ingredients: In a separate bowl, combine the all-purpose flour, baking powder, baking soda, and salt.

5-Alternate adding dry ingredients and buttermilk: Alternately add the dry ingredients and buttermilk (or milk) to the wet mixture, starting and ending with dry ingredients. Mix until just combined, being careful not to overmix.

6-Fold in sprinkles: Gently fold in the sprinkles by hand, using jimmies to prevent color bleeding.

7-Bake the cake layers: Divide the batter evenly between the prepared pans. Bake for 25 to 32 minutes or until a toothpick inserted in the center comes out clean.

8-Cool the cakes: Cool the cakes in the pans for 15 minutes, then transfer to wire racks to cool completely.

9-Soften ice cream: Allow the ice cream to soften for 15-20 minutes for easier spreading. You want it pliable but not completely melted.

10-Level cake layers: Level the cooled cake layers by trimming any domes with a serrated knife. This makes for even stacking.

11-Line springform pan: Line an 8-inch springform pan with plastic wrap and place a cake board at the bottom for support.

12-Spread ice cream on first cake layer: Place one cake layer in the pan and spread the softened ice cream evenly over it, creating a smooth layer.

13-Place second cake layer inverted: Place the second cake layer inverted on top of the ice cream. This makes the flat bottom of the cake face upward for easier decorating.

14-Wrap cake tightly with plastic wrap: Wrap the cake tightly with plastic wrap twice to prevent ice crystals from forming.

15-Freeze the cake: Freeze for 2 to 4 hours until firm. For best results, leave it overnight.

16-Chill mixing bowl and beaters: Chill a mixing bowl and beaters before starting to help the cream whip properly.

17-Beat whipped cream: Beat the heavy whipping cream until soft peaks form, then gradually add the powdered sugar and sprinkles until stiff peaks form.

18-Transfer whipped cream to piping bag: Transfer the whipped cream to a piping bag fitted with your desired tip.

19-Pipe whipped cream on cake: Remove the cake from the pan and pipe whipped cream along the edges and top.

20-Smooth and decorate: Smooth gently with a spatula, and decorate with additional whipped cream and sprinkles as desired.

21-Refreeze decorated cake: Refreeze the decorated cake for 30 to 60 minutes before serving to make sure the ice cream is firm.