Banana cream Filling:
One ripe banana
Yellow food coloring
Blend cream cheese and powder sugar with mixer. Add a teaspoon vanilla. Mix in smashed banana and a squeeze of lemon juice. Drop a couple of drops of yellow food dye. Chill for 15 min. Cut into muffin a desired filling area and fill. You may cut top on the filling.
I made up the filling so I don't know exact measurements. I started with about 3/4 cup cream cheese and continued to add sugar to taste. then added the rest.