Put muffin mix in a large bowl.
In another bowl,, combine egg, water and melted butter.
Add all at once to muffin mixture and stir just until moistened.
Spoon batter into prepared muffin tin, filling cups two-thirds full.
Bake in preheated oven for 20 to 25 minutes.
Cheese Muffins: Add a small piece of Cheddar cheese in the center of each muffin before baking.
Jelly Muffins: Fill cups only half full with batter.
Put 1 tsp (5 mL) of your favorite jelly in center of each muffin and top with remaining batter.
Bake as directed.