Line 16 heart-shaped plastic cookie molds with plastic wrap (leaving about a 1-inch overhang); coat with vegetable spray. Set aside.
In a large mixing bowl, combine the marshmallows and butter.
Microwave on high for 2 minutes, stir, and microwave again for 1 minute. Remove the bowl from the microwave. Note: If you prefer to use the stove top, heat marshmallows and butter on low heat; stir to mix; and slowly stir in cereal.
Stir in the cereal. When the ingredients are well mixed, press mix into each of the molds. Press the remaining mix into an 8-inch x 8-inch greased pan and then cut into squares for extra treats.
Let treats harden in the molds for at least 1 hour.
Carefully lift hearts from the molds by pulling on the plastic wrap. Press a Popsicle stick at least 1 inch deep into the middle of each heart.
In a small bowl, melt candy melts or chips in microwave for 2 minutes on medium. Stir once after a minute. Reheat candy coating for 40 to 60 seconds if it hardens during dipping.
Dip a corner of each heart into the melted candy coating. Lay the hearts on waxed paper; add sprinkles. Let set for 30 minutes.