Place cupcakes on baking sheets, spacing them 2 or 3 inches apart. Tint buttercream with food color. Fit the pastry bag with No. 867 star tip, and fill halfway with tinted buttercream.Advertisement
Pipe a swirl of icing onto cupcakes, refilling pastry bag when necessary. If making ahead, refrigerate, uncovered, until ready to use, up to 6 hours.
Arrange cupcakes on cake stand. Insert the stamped fondant heart into the cupcakes. If they have been refrigerated, you may need to wait about 30 minutes to let the icing soften slightly before inserting fondant hearts.