Position rack in the center of oven; preheat oven to 400°.
Prepare muffin tin—spray indentations and rims with nonstick spray.
In a bowl, whisk flour, sugar, baking powder, salt, and pepper; set aside.
In another bowl, whisk the egg, melted butter, and mustard until blended.
Gently whisk in the beer until the foaming subsides, then add the cheese.
Finally, stir in the flour mixture with a wooden spoon until moistened.
Fill prepared muffin tins 3/4 full; bake 20 minutes or until muffins have lumpy brown tops and a pick comes out almost clean.
Set pan on a wire rack to cool for 10 minutes; gently tip each muffin to one side to make sure it’s not stuck (gently rock back and forth to release it); remove muffins from pan and cool for 5 minutes on wire rack.
*Beer Blue Cheese Muffins—decrease Cheddar to 3/4 cup and add 1/2 cup crumbled blue cheese, such as Gorgonzola or Stilton, with the remaining cheese; proceed as directed.
*Beer Caraway Muffins—Add 1 tablespoons caraway seeds with the flour; proceed as directed.
*Beer Celery Seed Muffins—add 1 tablespoon celery seeds with the flour; proceed as directed.
*Cider Muffins: substitute hard cider for the beer; proceed as directed.