Preheat oven to 400°F. Spray a (12 muffins) muffin pan with cooking spray. Cut cranberries into halves, divide evenly into muffin cups in pan. Spoon 1 tsp. of butter into each cup, sprinkle evenly with brown sugar.
In mixing bowl, stir together flour, baking powder, sugar, salt and raisins. In small bowl, beat egg, mix in milk and remaining melted butter. Add liquid mix to flour mix, stirring until dry ingredients are just moistened. Spoon batter over cranberries, dividing it evenly.
Bake for about 30 minutes or until golden brown. Let stand in pan for 5 minutes. Then, carefully turn muffins out, serve upside-down.