Preheat oven to 350 F (175 C). Prepare baking cup pans with about 15 cupcake liners.
Add granulated sugar and vanilla bean to the bowl of a stand mixer, and beat on medium speed for about 30 seconds until blended. Add in the cake flour, baking powder, baking soda and salt, and beat for an additional 1 minutes until well-mixed. Add butter and mix on medium-low speed for about 2 minutes until well combined and a little crumbly.
In a separate small mixing bowl, whisk together eggs, Greek yogurt (or sour cream), and vanilla extract until smooth. Add the egg mixture to the flour mixture and beat on medium speed until just combined.
Slowly add milk and mix on low speed until just combined. The batter will be very thin and liquid.
Fill cupcake liners just over 1/2 full. Bake for 14 minutes and then test to see if they are done. They are done when a toothpick comes out without wet batter stuck to it. Remove and let cool on a cooling rack. Once the cupcakes have reached room temperature, frost with the caramel frosting (instructions below).
TO MAKE THE FROSTING:
Beat the butter in the bowl of an electric stand mixer fitted with the paddle attachment on medium-high speed until light in color and fluffy, about 3 minutes. Reduce speed to low, add powdered sugar, and mix until completely incorporated. Turn off the mixer, and then add caramel. Beat frosting on low to combine, and then increase to medium-high and beat until airy and thoroughly mixed, about 2 minutes. Store in an air-tight container and refrigerate if not using immediately. **If your frosting is too thin, add an extra 1/4-1/2 cup of powdered sugar to thicken.