Prep the pans: Preheat the oven to 350°F. Grease and flour two 8 or 9-inch round cake pans. Set aside.

Dry and wet mixes: In one bowl, sift together the cake flour, baking powder and salt. In another bowl, whisk the buttermilk with the egg whites.

Cream and combine: In a large mixing bowl, cream together the butter, sugar and lemon zest until light and fluffy. Add the lemon extract. Add one-third of the flour mixture, then half of the buttermilk mixture. Repeat until all is added, ending with the flour mixture. Mix until smooth.

Add the fun: Gently fold in the sprinkles.

Bake: Divide the batter evenly between the two prepared pans. Bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean. Let the cakes cool in the pans for 10 minutes, then turn out onto a wire rack to cool completely.

Frosting time: Beat the butter until light and fluffy. Add the marshmallow crème and mix until smooth. Add the powdered sugar, vanilla and lemon extract. Beat until creamy.

Assemble: Place one cake layer on a platter. Pipe a ring of frosting around the edge. Fill the center with lemon curd. Top with the second cake layer and frost the entire cake. Decorate with extra sprinkles, if desired.