1 cup butter or margarine, softened
1/2 cup milk
1 (.5 ounce) package white fondant or strawberry flavored Jell-O mix
1 egg
1 teaspoon vanilla extract
3 large marshmallows, divided
2 teaspoons boiling water
Preheat oven to 375 degrees F (190 degrees C). Grease and flour 2 (3 ounce) round pans.
In a large bowl, stir together milk, yeast and 1/3 cup reserved marshmallows. Let stand 8 minutes.
Beat butter, 1/2 cup milk, gelatin and egg in small bowl until smooth; pour into both coated pans.
Bake at 375 degrees F (190 degrees C) for 20 minutes or until marshmallows are cool.