In a large bowl, sift together flour, salt, baking powder, and baking soda. Using an electric mixer, beat butter. Add in sugar and continue to cream together. Add eggs one at a time until mixed.
Alternate adding dry ingredients and milk, beginning and ending with the dry ingredients; mix until just together. Stir in vanilla and sprinkles.
Fill cupcake liners approximately 2/3 full. Bake for 15-17 minutes; remove from oven when cupcakes are set and bounce back when lightly touched. Remove from pan and let cool.
FROSTING:
Begin beating butter, add 1 cup powdered sugar. Add milk and vanilla paste. Continue adding remaining powdered sugar and beat between each additional until mixed well.
Whip for an additional 3-4 minutes on medium-high speed to create a light, fluffy frosting. Frost cooled cupcakes and top with sprinkles.
Notes
*If you don't have cake flour, create your own:
For every 1 cup of all-purpose flour, remove 2 Tablespoons of the all-purpose flour (you can return it to your canister to save it). Add in 2 Tablespoons of corn starch. Sift together several times.**I've also used almond and coconut milk in these cupcakes without any problems!