Adapted from a few recipes I found online
2-3 Tbsp olive oil
2 lb potatoes, peeled and sliced thin
1 lb onions, sliced thin
1 Tbsp minced garlic
1/2 - 1 tsp finely chopped dried rosemary
2 tsp salt (or to taste)
1/2 tsp pepper (or to taste)
1/2 c milk
4 whole eggs
10 egg whites
1/2 c shredded parmesan cheese
1/2 c shredded mozzarella cheese
Preheat oven to 400F
In large oven-safe pan (I use a 5 qt saute pan with metal handles), heat olive oil on medium-high and cook potatoes 5-10 minutes until soft. Add onions, garlic, and spices and cook until onions are soft and potatoes are turning golden brown, about another 10 minutes.
In a large bowl, whisk milk and eggs, then mix in parmesan cheese. Pour over potato-onion mixture and cook 2-3 minutes until eggs begin to set. Sprinkle mozzarella cheese evenly on top.
Place pan in oven and cook for 15+ minutes, until cheese on top is golden brown and eggs are set (may take up to 30 minutes, depending on the size of the pan and how deep the frittata is).
Per Serving: 263 cal; 27 g carb; 11 g fat; 15 g protein; 312 mg sodium; 3 g sugar