Heat oven to 350ºF. Line cupcake pans with liners; set aside. Whisk together flour, baking powder and salt, set aside.
In a mixing bowl or bowl of an electric mixer, beat together butter and sugar until light, about 3 minutes. Add eggs and vanilla and combine, scraping sides of bowl. Stir in flour mixture and milk alternately in 3 parts, starting and ending with flour.
Stir in sprinkles if using. Divide batter among liners; fill standard cups ¾ full and mini cups just below the top.
Bake until tops spring back when lightly pressed, about 20 minutes for standard, 15 minutes for minis. NOTE: Cupcakes stay light in color, so don't wait until they are golden. Cool completely on racks before frosting.
Make Vanilla Buttercream
In a mixing bowl or bowl of an electric mixer, beat butter until smooth and creamy, about 2 min. Add confectioners' sugar ½-cup at a time, mixing well and scraping down sides of bowl occasionally.
Beat in vanilla and salt; stir until smooth. Divide and color with food coloring as desired.
Frost cooled cupcakes, decorate with sprinkles and serve.
Notes
Unlike many vanilla cupcake recipes, this one doesn't brown. Don't look for a golden color as the cake bakes, if you see it they are overdone!
Click over to the Fluffy Vanilla Frosting post for more information and tips on American buttercream, and how to use it for decorating.
Storage: Frosting will keep covered in the refrigerator for up to a week. Bring to room temperature and stir before using, if chilled. Unfrosted cupcakes will last up to four days at room temperature, if kept in an airtight container.