Preheat the oven to 375 degrees F and grease a standard muffin tin with nonstick spray.
Place all ingredients into a medium bowl and stir together gently to combine.
Divide the batter among the prepared muffin tin, filling each about ¾ full.
Bake for 18-20 minutes or until the edges are lightly golden brown and a cake tester inserted into the center comes out clean.
Remove from oven, let cool in the pan for a minute or so, then transfer to a wire rack to cool at least slightly.
Serve warm with butter.
