Preheat the oven to 350 F. Line a 12 cup muffin pan with paper liners. In a large bowl, whisk together flour, sugar, salt, and baking powder. Add in milk, vegetable oil, eggs, and vanilla extract. Whisk until smooth.
Fold in the sprinkles. Evenly divide the cupcake batter between the prepared muffin pan. Bake for 15-18 minutes. Let cool completely before frosting.
For the frosting, mix all of the ingredients together until smooth. Pipe or spread frosting onto each cupcake.