Preheat the oven to broil.
Add the olive oil to a large oven-safe skillet and heat over low heat for 30 seconds.
Add the garlic and cook over low heat for 3 minutes.
Add the oregano, crushed red pepper flakes, diced tomatoes, and white beans, and increase heat to medium.
Simmer uncovered for 8-10 minutes until tomatoes are softened and most of the juice has evaporated.
Top with mozzarella cheese.
Place under the broiler for 2-3 minutes, if desired, for brown and bubbly cheese. If you do not have a broiler-safe skillet, simply top with mozzarella and cover the pan. Let sit over low heat for 2-3 minutes until the mozzarella has melted.
