Preheat the oven to 350°F. Grease a 12-cup non-stick muffin tin with oil spray.
Place the cornmeal, flour, sugar, salt and baking powder in a bowl and whisk to combine. Stir in the cheese and diced peppers.
Beat the egg in a second medium bowl. Mix in the ale, buttermilk and butter. Mix the wet ingredients into the dry until just combined. Spoon the batter into the muffin tin.
Bake for 18 to 20 minutes, or until a cornbread muffin springs back when gently touched. Cool 15 minutes, and then carefully unmoulded. Serve warm or at room temperature.