Preheat oven to 375 degrees F. Lightly coat a 9x13” pan with spray or oil or line with parchment paper.
In a large bowl add oats, carrots, raisins and ½ cup of nuts. Stir to combine.
In a medium bowl whisk milk, greek yogurt, maple syrup, eggs, flax, cinnamon and salt. Add to oat mixture and stir until combined.
Pour oat mixture into the prepared pan evenly.
Bake for 30-35 minutes until the center is set.
While oats bake, assemble frosting. Mix all frosting ingredients in a small bowl until well combined. Allow oats to cool at least 15 minutes and frost the top evenly. Top with extra chopped walnuts.
Notes
If making ahead or you expect to have leftovers, save the frosting for right before serving.To make these 100% gluten free, be sure to use certified gluten-free oats.