Preheat oven to 350° F. Line cupcake pan with paper liners. Allow all ingredients to reach room temperature.
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. Beat in yogurt until incorporated, batter will still be lumpy.
In a small bowl, whisk together egg, egg yolk, and vanilla bean. Beat egg mixture into batter until smooth. It will be very thick and sticky. Divide batter evenly among cups in pan, about 1/3 cup of batter in each. Using an ice cream scoop makes this very easy. Using a small spoon or off-set spatula, smooth the top of the batter in each cup.
Bake for 20 minutes for standard cupcakes (12 for mini), or until a toothpick comes out clean. Cool in pan for 5 minutes, then remove cupcakes and cool completely on a rack.
While cupcakes cool, make frosting. 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. This step can be done to taste. Beat in salt, then vanilla. Last, briefly beat in heavy cream.