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.
Evenly divide the cupcake batter between the prepared muffin pan. Bake for 15-18 minutes. Let cool completely before frosting.
In a large bowl, mix butter with powdered sugar, milk, and vanilla extract until smooth. Frost cupcakes, decorate with chocolate chips to look like a ghost.