Preheat an oven to 350F and line a baking sheet with parchment paper or cooking spray.
Mix the oats, protein powder, salt, and baking powder in a large bowl.
In a separate bowl, mash the banana before adding the egg. Stir well.
Add the banana and egg to the dry ingredients and stir until evenly mixed.
Fold in the chopped nuts and cranberries.
Spoon the mixture into 8 small circles on the baking sheet. Use a rubber spatula or the backside of the spoon to flatten the cookies and round the edges.
Bake for 8-10 minutes or until the centers are cooked through. The cookies should still be a bit soft but golden brown on the bottom. Do not over bake. Let them cool for a few minutes and dive in.