Preheat oven to 350 degrees F.
In a large bowl, sift the cake flour, baking soda, baking powder, and salt, set aside.
In a separate large bowl, mix the butter and sugar until smooth.
Add the eggs to the butter mixture and mix until well incorporated.
Stir in the vanilla bean paste, vanilla extract, sour cream, vegetable oil, and milk.
Add the flour mixture to the butter mixture and mix until well combined, be careful not to over mix.
Using an ice-cream scoop, scoop the batter evenly into your muffin tin and bake for 14-16 minutes.
To make the frosting, mix the unsalted butter for about 2 minutes.
Add the powdered sugar, vanilla extract, milk, heavy cream, a pinch of fine salt or 1 tsp lemon juice and mix for about 5 minutes on medium-high speed.
Frost your cooled cupcakes with a piping bag or an offset spatula sprinkle some Nonpareils if desired and enjoy!