INGREDIENTS
1 cup
unsalted butter, softened to room temperature
1
and 1/2 cups (300g) granulated sugar
1
egg + 1 egg yolk, room temperature preferred
2 tsp
vanilla extract
3 cups
all-purpose flour (careful not to overmeasure)
1
and 1/4 teaspoons baking soda
1/2 tsp
cream of tartar1
1 tsp
cornstarch
1/2 tsp
salt
1 cup
sprinkles, plus more for decor on top of frosting2
3/4 cup
unsalted butter, softened to room temperature
2
and 1/4 cups (270g) confectioners' sugar
3 tbsp
heavy cream or half-and-half3
1 tsp
vanilla extract
1/8 tsp
salt