Heat the olive oil in a large skillet over medium-high heat. Add the sweet potato and cover. Cook, stirring occasionally, until the sweet potato has softened but is still slightly firm, about 5-7 minutes.

Add the mushrooms and garlic and continue cooking until the mushrooms have softened, about 3-5 minutes.

Move the vegetables to one side of the skillet and brown the sausage. If you're using pork sausage, drain any excess fat. Once cooked, stir the sausage in with the vegetables.

Add the chopped kale and cover the skillet. Cook until the kale has wilted, about 2 minutes. Stir all the ingredients until they're thoroughly mixed. If water or moisture remains at the bottom of the skillet, continue cooking until the water evaporates.

Preheat the oven to 375° F. Lightly oil a large casserole dish. Transfer the vegetables and sausage to the casserole dish and allow the mixture to cool for 10 minutes.

Crack the eggs into a large mixing bowl and whisk until well combined.

Pour the egg mixture into the casserole dish and use a wooden spoon to spread it so that the eggs and veggies are evenly distributed.

Sprinkle the cheese on top and bake in the preheated oven for 45-55 minutes, or until the casserole has set and the cheese is golden brown.

Allow the casserole to cool 10 minutes before cutting large slices and serving with your guests' choice of toppings.