Step 1: Preheat the Oven - Start by preheating your oven to 375°F (190°C).
Step 2: Cook the Sausage and Onions - In a large skillet, heat olive oil over medium heat. Add the sausage and cook until browned. Add onions and sauté until translucent.
Step 3: Prepare the Spinach - Ensure your frozen spinach is thawed and well-drained.
Step 4: Mix the Egg Mixture - In a bowl, whisk eggs, salt, and pepper. Stir in cheese, spinach, sausage, onions, and sun-dried tomatoes.
Step 5: Transfer to Baking Dish - Pour the egg mixture into a greased baking dish.
Step 6: Bake - Place in the oven and bake for 30-35 minutes, until set and golden.
Step 7: Cool and Serve - Allow to cool for a few minutes before slicing. Enjoy warm or at room temperature!