Preheat the oven to 350°F. Lightly butter and flour a 9x9-inch pan.
Whisk together the melted butter and sugar in a bowl. Add the egg and vanilla extract and whisk to combine.
Add the flour, baking soda, baking powder, and salt, and mix it all together. Add the butterscotch chips or other mix-ins (up to 1 cup total). Pour into the pan and spread evenly. Bake for 18 to 25 minutes or until a tester inserted into the center comes out clean.
Allow to cool. Cut into squares or football shapes and decorate with white icing to make laces for the football.