Line an 8 in. x 8 in. baking pan with parchment paper for easy release. It is helpful to line the pan in both directions, using 2 sheets of parchment paper.
Add oats, cheerios, pecans, dried cranberries, and chocolate chips in a large bowl. Stir until evenly combined.
Add honey and peanut butter to oat mixture and stir until it is evenly distributed.
Sprinkle in cinnamon and ground flaxseed. Stir until all ingredients are evenly combined.
Press into a lined 8 in. x 8 in. pan and freezer for 1 hour.
Cut the pan into 12 pieces (2x6).