How to Make It
Preheat broiler to high with oven rack in upper middle position.
Heat an 8-inch ovenproof skillet over medium. Coat pan with cooking spray. Add kale and roasted butternut squash; cook 2 to 3 minutes.
Whisk together eggs, yogurt, salt, and pepper. Add eggs to pan, and cook 2 minutes, stirring slowly and tilting the skillet a few times so runny parts hit the pan.
Place pan under broiler; broil 1 minute or until eggs are almost set. Top frittata with avocado.