In lge. mixing bowl, beat eggs & milk, then whisk in melted butter. Stir in mix just until it is moistened; don't over-mix. Stir in raisins if desired. Divide among muffin cups and bake in preheated 425 F. oven for 20 min., or until muffins are firm and shrink back from sides of cups slightly. Serve immediately. Leftovers may be stored in plastic bags in 'fridge for later rewarming in moderate oven or mircowave.