Chocolate Peanut Butter Oatmeal Bars

0 Line a muffin pan with paper liners or use a silicone muffin pan. 
1 In a large microwave-safe bowl, melt 1 cup creamy peanut butter and the honey until smooth and shiny. Heat the mixture in 20 second intervals, stirring after each. It should take about 40 seconds. 
2 Stir in the oats, chia seeds, and flax seeds until even. Divide the mixture between the spaces in the muffin cups, pressing down very firmly to compress. 
3 In a small microwave-safe bowl, combine the chocolate chips, ⅓ cup peanut butter, and coconut oil (if using). Heat in 20 second intervals, stirring after each, until the chocolate chips are completely melted. Pour the chocolate over the bars. Sprinkle M&Ms over top. 
4 Refrigerate the bars until the chocolate is set, about 30 minutes. Keep the bars in the refrigerator for up to a week. Serve chilled.