Preheat the oven to 375*F and spray a 9-inch springform pan with olive oil. Line the outside of the pan with foil and set the springform pan on a large baking sheet then set aside.

Remove excess water from the zucchini noodles by placing the noodles in a clean kitchen towel and squeeze the noodles until no additional water is released. Set aside.

Heat the olive oil in a medium skillet for medium-high heat.

Add in the onions and garlic, season with salt & pepper and cook until onions soften, 2-3 minutes stirring occasionally. Add in the tomatoes and cook another 3-4 minutes until tomatoes soften and onions begin to caramelize then remove move from heat and let cool slightly.

In a medium-sized bowl whisk together the milk, flour, and cheese. Add in the eggs and whisk well.

Fold in the onion-tomato mixture, zucchini noodles, basil, and meat (if using). Season with additional salt and pepper if desired.

Pour the mixture into the prepared pan and cook for 50-55 minutes until the center is set.

Remove from oven and let cool completely.

Release the frittata from the pan and cut into 6 pieces.

Once fully cooled, cover and refrigerate for up to 5 days.