Grease the baking dish generously with butter or a nonstick spray.

Melt the butter in a large saucepan over medium heat until it's bubbly and fragrant. Add in the mini marshmallows, stirring continuously until they're completely melted and smooth—this should take about 4-5 minutes.

Combine the red food coloring into the melted marshmallow mix, stirring until it's evenly blended throughout.

Fold in the Rice Cereal gradually, ensuring it's all coated with the sticky marshmallow mixture.

Transfer the mixture into the greased baking dish, pressing it down evenly.

Cool the treats for about 10 minutes, then use heart-shaped cookie cutters to cut them into shapes.