Coarsely chop kale and slice mushrooms. Set veggies aside until ready to use. Brown sausage in a medium skillet. Add mushrooms and kale and cook 2-3 minutes until lightly softened.
Crack eggs into a bowl and beat until well combined. Add the eggs into the sausage mixture, stirring everything together with a fork until eggs are evenly distributed throughout the pan.
Cover and cook 5-6 minutes. While frittata is cooking, preheat the broiler to medium temperature. Add cheddar to the top of the frittata and place frittata under broiler for 3-4 minutes until top is a golden brown.
This recipe freezes well and can be used for quick meals in the future.