HEAT oven to 375° F.
BEAT first 5 ingredients with mixer until blended; spoon into 12 paper-lined muffin cups.
MEANWHILE, beat cream cheese, butter and vanilla in large bowl with mixer until creamy. Turn the mixer to low speed and slowly beat in sugar.
FILL a piping bag with a large open star tip on it with 1 cup of frosting. Hold the piping bag straight up, start frosting from the outside edge, and begin swirling around the outside edge. Continue squeezing with constant pressure as you work around the edge of the cupcake and into the center. Finish the spiral in the center, release pressure on the bag, and pull straight up.
IMMEDIATELY place one marshmallow on center of frosting.
ENJOY within 3 hours or cover with loose plastic wrap and keep refrigerated.