Place two muffin pans in the oven and preheat the oven to 375°F.

In a large mixing bowl, whisk together the eggs, heavy cream, half the parmesan cheese, salt, and pepper until well combined.

In a cast iron skillet, melt the butter over medium heat. Add the red onion and sauté for about 2-3 minutes until softened. Add garlic and red pepper and sauté until tender, about 3-4 minutes. Add the spinach and wilt, 2 minutes.

Remove the preheated muffin pans from the oven. Spray the wells of the muffin pans with nonstick cooking spray and distribute the vegetable mixture evenly across the muffin wells.

Pour the egg mixture over the sautéed vegetables, about ¼ cup per well. Sprinkle the crumbled goat cheese evenly over the top of the eggs and top with remaining parmesan. The preheated muffin pans will begin to set the bottom of the egg mixture—that’s a good sign! The tops should still be runny.

Transfer the muffin pans to the preheated oven and bake for 8-10 minutes or until the eggs are set and the cheese is melted and slightly golden.

Remove mini frittatas from the oven and let cool in the pan for 3-5 minutes before loosening edges with a butter knife. Remove individual frittatas from the muffin pans and serve warm.