Preheat the oven to 375 degrees Fahrenheit.
Sift together the flour, baking powder, baking soda, and salt into a bowl.
In another bowl, beat together the sugar and egg until light and fluffy. Add in the oil or butter and milk, and mix until well combined.
Add the wet ingredients to the dry ingredients, and mix until just combined. Do not overmix!
Grease a muffin tin with cooking spray or butter, and fill each muffin cup about three-quarters full with batter. Bake for 18 minutes, or until a toothpick inserted into the center comes out clean. Let cool for a few minutes before transferring to a wire rack to cool completely.