In a saucepan, melt the butter over low heat. Stir in the marshmallows until melted and combined. Cook for an additional two minutes while stirring constantly. Remove from heat.
Stir in the cereal until blended and well coated.
Press the cereal mixture into a greased mini muffin pan to form a bowl.
Allow to cool and place yellow M&M's into each bowl.
Recipe by Sugar, Spice and Family Life at https://sugarspiceandfamilylife.com/2017/03/mini-pot-of-gold-cocoa-krispie-treats-recipe.html