Line a metal muffin pan with paper liners or use a silicone muffin pan.
For the oat layer, combine quick-cooking oats, honey, peanut butter, and mini chocolate chips in a bowl. Mix well and add 2 tablespoons of the mixture into each muffin cup, pressing firmly.
For the chocolate layer, melt dark chocolate and coconut oil in a microwave-safe bowl. Spoon 2 teaspoons of melted chocolate over each oat layer and swirl to cover evenly. Freeze for 5 minutes.
For the peanut butter layer, microwave peanut butter and coconut oil until smooth. Spoon 2 teaspoons over the chocolate layer and swirl again. Top with mini M&M’s and mini chocolate chips.
Freeze the muffin tin for 30 minutes to set.
Once firm, remove oat cups from the pan and store in a freezer bag.