Homemade Funfetti Cake

and 2/3 cup (210g) all-purpose flour, careful not to overmeasure

baking powder

baking soda

salt

or 115 g) unsalted butter, melted

granulated sugar

packed light brown sugar

large egg

yogurt  (plain or vanilla; or greek yogurt; or sour cream)

milk (cow's milk; or soy milk; or almond milk)

vanilla extract

sprinkles (not nonpareils)

or 230g) unsalted butter, softened to room temperature

(360-480g) powdered (confectioners') sugar

heavy cream (see note above about substituting milk or half-and-half)

and 1/2 teaspoons vanilla extract

salt, as needed