For Cupcakes

Preheat oven to 350º F. Line your pan with liners, or if baking cakes grease the pans with butter or coconut oil, then line with a parchment circle cut to fit the bottom.

In a large bowl combine flour, salt, baking powder, and sugar. Beat on low briefly to combine. Add butter, and mix on medium speed until coarse crumbs form, less than a minute. Blend in the sour cream, and you’ll find yourself with a lumpy batter.

Whisk together egg, egg yolk, and vanilla bean or paste in a small bowl and add to batter. It will be very thick and sticky.  Divide evenly among cups in pan (I like my ice cream scoop for portioning).

Bake for 18-20 minutes for standard cupcakes (12-14 for mini), or until a toothpick comes out clean. Cool in the pan for 5 minutes, then remove cupcakes and cool completely on a rack.

For Buttercream 

With a hand mixer, or a stand mixer with a whisk attachment, whip butter on high speed for at least three minutes, until it is light in color and doubles in volume. In one cup increments, beat in sugar (use more or less depending on taste and how sweet you like).  Beat in salt, vanilla and last the heavy cream.

For a fancy yet incredibly easy touch, load up your buttercream into a pastry bag (or large baggie, corner snipped) fitted with a star or drop flower tip.   Store covered for up to three days. Unfrosted cupcakes can be frozen as long as you can take the taunting from inside your freezer!