Step 1

Preheat the oven to 350°F. Lightly grease and flour two 8-inch round cake pans and line the base with rounds of parchment paper.

Step 2

Sift flour, baking powder, baking soda and salt into a medium bowl and whisk to blend evenly.

Step 3

Make the cake batter. Combine soft butter, oil, sugar and vanilla in a large bowl and beat with an electric hand mixer for 2 minutes until pale and fluffy. Beat in egg until well incorporated. Add egg whites and beat until well combined and smooth. Mix in sour cream. Sift in half of the flour over the wet mixture and mix it in slowly. Gradually beat in half of the milk. Mix in remaining flour and then rest of the milk. Beat on high for the last 5 seconds to emulsify the batter. Fold in sprinkles.

Step 4

Divide the batter evenly between the prepared pans and bake for 25-28 minutes until lightly golden and a skewer inserted into the center comes out clean. Transfer pans to a wire rack and let cool completely.

Step 5

Make the frosting. Place chopped white chocolate into a large bowl. Pour ½ cup of cream into a 1-quart stainless steel saucepan with the scraped vanilla bean seeds (and I also add the scraped pod because there are still lots of seeds in there!) and place over medium heat. Watch it as it comes to a simmer. Once simmering, immediately pour it over the chopped chocolate, cover the bowl and let stand for 2 minutes. Uncover the bowl and whisk until the chocolate is completely melted and the mixture is smooth and silky. Let it cool for 5 minutes so it is no longer hot, and then whisk in remaining cold cream. Place the bowl in the fridge and chill for at least 2 hours or overnight until completely cold. If you choose to chill overnight, then cover the bowl after 20 minutes, and in this case you may wish to make the frosting base first and then make the cake layers the next day.

Step 6

Once thoroughly chilled, add the vanilla extract and beat with an electric hand mixer or stand mixer fitted with the whisk attachment on medium speed until thick and fluffy. This will take about 2 minutes but it depends on your mixer. Watch the video to see the consistency you should be looking for.

Step 7

Make the cream filling. Combine cold cream, sugar and vanilla in a medium bowl and whip to firm peaks using an electric hand mixer. Gently mix in Vanilla Whipped Ganache Frosting.

Step 8

Assemble the cake. Place one cake layer on a serving plate. Fill a piping bag with about 1 cup of frosting and pipe around the circumference of the cake to build a wall that will keep the filling from squeezing out. Use an offset spatula to spread the cream filling over the top of the cake within the frosting border. Place the other layer on top so it aligns with the sides of the bottom layer. Cover the entire cake with frosting and use a large offset spatula to even out the sides and make swooshes and swirls on the top layer. Decorate with sprinkles (as many as you’d like!).