Preheat oven to 400°F. Line a 12-cup muffin pan with paper liners. Lightly spray liners with cooking spray.
Set aside 12 cherries. Chop remaining cherries. Place cherries on a paper towel to drain.
In a bowl using an electric mixer, beat margarine and cream cheese on medium speed until creamy. Add Splenda Stevia Sweetener and mix well. Add egg, mixing until blended.
Add about ½ the flour and beat on low speed to combine. Add milk and mix on low to combine. Add remaining flour and blend well; do not overmix. Fold in chopped cherries.
Spoon one tablespoon of batter into each muffin cup. Place a cherry in the center of each cup. Top with remaining batter, filling muffin cups ¾ full.
Bake for 25 minutes or until muffins are lightly browned. Remove from pans immediately and cool on wire racks.