Preheat oven to 400 degrees F.
Spray a stoneware baking dish if using or heat your cast iron skillet on the stove top.
Cooking spray
Place cubed sweet potatoes in a glass dish and pour 1 tbsp water over the top.
1 medium sweet potato peeled and diced
Microwave the potatoes on high for 2 minutes, loosely covered.
1 medium sweet potato peeled and diced
Sauté the onions and colored bell peppers in olive oil over medium heat.
1 tbsp extra virgin olive oil, 1 red bell pepper diced, 1 sweet or yellow onion sliced, 1 yellow bell pepper diced
I put a pinch of salt and a little bit of cracked pepper on my veggies as they are sautéing. It's important to season as you go as it helps to create layers of flavor throughout the dish.
½ tsp kosher salt, Fresh ground pepper
Once partially cooked, add the fresh spinach and continue to sauté until wilted.
4 cups fresh spinach
Add the partially cooked sweet potatoes, stir and cook down until all vegetables are crisp tender.
1 medium sweet potato peeled and diced
Spread the sautéed vegetables in an even single layer in your stoneware dish. (It ends up being about 2-3 cups of vegetables when fully cooked down.)
Whisk the eggs.
8 large eggs
Add the milk, fresh thyme (removed from the sprigs), 1/2 teaspoon salt, and cracked black pepper (to taste) to your beaten eggs. Whisk together.
½ cup whole milk, ½ tsp kosher salt, Fresh thyme, Fresh ground pepper
Add the 3 cheeses to the egg/milk mixture and give it a good stir to combine.
½ cup fresh shredded aged sharp cheddar cheese, 1/3 cup honey goat cheese, ¼ cup grated parmesan cheese
Pour the egg mixture over the cooked vegetables and ensure it evenly covers the veggies.
Bake frittata in the oven at 400 degrees F for approximately 20-22 minutes or until the egg is set. Do not overcook or the eggs will be rubbery.