Preheat oven to 375 degrees F. Meanwhile, make the caramelized onions.

In a 10 or 12-inch cast-iron skillet over medium heat and add the olive oil and butter. Slowly sauté the onions until they are deeply caramelized, stirring occasionally, about 20 minutes. 

After caramelizing onions add in chopped broccoli cooking only about 5 minutes.

TIP: If browned bits build up on the bottom of the pan while caramelizing the onion, deglaze it with a touch of water.

While the onions and broccoli cook, whisk together the eggs, half and half, thyme and parsley in a mixing bowl. Season with salt and pepper to taste and set aside. 

Once the onions are nicely caramelized, deglaze with the sherry and reduce until dry. Stir in the spinach and cook until just wilted. Season to taste with salt and pepper.

Increase the heat to high. Pour the egg mixture into the pan and stir once to combine. Sprinkle the top with the roasted broccoli and crumbled goat cheese and feta.

Cook on the stovetop for 2 to 3 minutes without stirring to create a golden brown crust on the bottom of the frittata. Then, slide the pan right into the oven and continue to cook until the eggs are just set, about 15 minutes. 

Allow to cool for 5 minutes, and then invert the frittata onto a plate or cutting board. Slice into wedges and serve warm. Top with more fresh herbs and serve alone or with freshly dressed greens! Enjoy! Save prep time by using your leftover roasted veggies!