If it wasn't for the egg base, you'd think you were eating pizza! Yumm....
Source: Adapted from Everyday Food magazine, Oct. 2004
1 T. plus 4 t. olive oil
1 medium onion, finely chopped
1 c. sliced fresh mushrooms
6 large eggs
coarse sea salt
1 c. shredded mozzarella cheese (4 oz.), divided
2 garlic cloves, thinly sliced
1 c. (14.5 oz.) whole tomatoes with juice, or 2 c. fresh tomatoes, cut
1/4 c. chopped fresh basil
Preheat oven to 350 degrees. In a 10" ovenproof nonstick skillet, heat 2 t. oil over medium heat. Cook onion and mushrooms, stirring often, until soft, about 5 min. Cool completely.
In a large bowl, whisk together eggs, 3/4 t. sea salt, and 2 T. water. Stir in onion, mushrooms and 3/4 c. mozzarella.
In skillet, heat 1 T. oil over medium heat. Add egg mixture; reduce heat to low, and cook until beginning to set around the edges, about 3 min. Transfer to oven; bake until set, about 12 minutes.
Meanwhile, heat remaining 2 t. oil in a large skillet over low heat. Cook garlic until soft, 2 min. Add tomatoes, basil and 1/4 t. sea salt; simmer, breaking up tomatoes with a spoon, 5 minutes.
Spoon sauce over frittata; sprinkle with remaining 1/4 c. cheese. Return to oven; cook until cheese melts, about 1 minute.