Line muffin tin with cupcake liners and preheat oven to 375 degrees F.
In a large bowl, melt butter in the microwave until softened and almost melted. Add in the sugar and microwave for another minute.
In a separate bowl, mix together the dry ingredients (flour, salt, cocoa powder, baking powder). Set aside.
Add eggs and vanilla to the butter/sugar mixture and mix well. Add the dry ingredients to the wet ingredients slowly, being careful not to overmix.
Fill cupcake liners 3/4 full and bake for 8 to 10 minutes. Let cool completely before frosting.
For the frosting: Cream butter and sugar together in a bowl. Add vanilla and mix well. Next, add flour to the mixture, and then milk, being sure to scrape down the sides of the bowl. Fold in chocolate chips.