Roast the Sweet Potatoes: Heat the oven to 425°F. Spread the diced sweet potatoes on a baking sheet. Drizzle with olive oil and season with ¼ teaspoon kosher salt, ⅛ teaspoon of black pepper, garlic powder and smoked paprika. Toss gently to coat. Roast for 15 to 20 minutes, until tender. Remove from the oven and set aside to cool.
Cook the Bacon: While the sweet potatoes roast, cook the bacon in a small skillet until crisp. Transfer to a paper towel lined plate and let cool.
Cook the Vegetables: Remove all but 1 teaspoon of bacon drippings from the skillet. Add the onions and cook, stirring frequently, for 1 minute. Add the kale and ⅛ teaspoon of salt. Cook for 2 to 3 minutes, stirring occasionally, until softened. Remove from the heat and let cool slightly.
Prepare the Egg Mixture: Lower the oven temperature to 375°F. In a medium bowl, whisk together the eggs, heavy cream, the remaining ⅛ teaspoon of kosher salt, and ⅛ teaspoon of pepper until well mixed. Stir in the cheese. Gently fold in the roasted sweet potatoes, cooked vegetables, and crumbled bacon.
Bake: Lightly butter a 5×5 inch baking dish. Pour in the quiche mixture and spread evenly. Bake for about 25 minutes, until the quiche is set and lightly golden on top.
Notes
Even Sweet Potato Pieces: Cut the sweet potato into small, evenly sized pieces so they roast at the same rate and become fully tender.
Pre Cook the Greens: Cooking the greens briefly removes excess moisture and helps them blend evenly into the quiche.
Let It Rest: Let the quiche rest for a few minutes after baking so it finishes setting and is easier to serve.
If doubling this recipe, bake in a 6x8-inch baking dish or two 5x5-inch baking dishes.