Preheat your oven to 350°F (175°C) and lightly oil a cast-iron skillet with olive oil.

Add cubed sweet potatoes to the heated pan and sauté in olive oil over medium heat for about 5-7 minutes until tender.

Stir in the chopped red onion and minced garlic, cooking for an additional 3-4 minutes until the onions are translucent.

Introduce the chopped kale, sautéing for another 2-3 minutes until it wilts.

In a separate bowl, whisk together the eggs, half-and-half, kosher salt, and freshly ground pepper.

Pour the egg mixture over the sautéed vegetables and cook on the stovetop for about 2 minutes.

Transfer the skillet to the oven and bake for 30-45 minutes until the frittata is set.

Allow the frittata to cool slightly for about 5 minutes before slicing and serving.