Baked Feta Egg Casserole

Name: Baked Feta Egg Casserole
Ingredients: 1/4 c. olive oil; 2 pt. cherry tomatoes; 1/4 red onion, sliced; 1/2 tsp. salt, plus more for serving; 1/2 tsp. black pepper, plus more for serving; 1 7-8 oz. block of feta; Pinch of red pepper flakes, plus more to taste; 2 cloves of garlic, finely chopped; 1 12 oz. jar roasted red peppers, drained and chopped; 1/2 c. loosely packed basil leaves, chopped; 6 large eggs; Toast or focaccia, for serving