All purpose flour
Preheat oven to 350 degrees F. Grease 2 (8-inch) round cake pans. Line with parchment paper, then butter/spray with cooking spray.
In the bowl of a stand mixer (or use a hand-held mixer) beat together the melted butter, yogurt, eggs, sugar, vanilla, and buttermilk.
Pour the batter among the cake pans and bake 30-35 minutes, until the tops are just set and no longer wiggly in the center.
Make the buttercream. Add the butter and the cream cheese to the bowl of a stand mixer and whip until extra light and fluffy, about 3-4 minutes.