Preheat oven to 400 degrees F. In a large skillet, heat olive oil over medium-high heat. Add onion, garlic, and 1/8 teaspoon salt. Cook and stir for 5 minutes or until tender.
Stir in tomatoes and rosemary. Bring to boiling; boil gently, uncovered, 5 minutes, or until slightly thickened.
Stir in beans and half the Parmesan. Season to taste with crushed red pepper, salt, and black pepper. Transfer to a 2-qt. rectangular baking dish.
Top with remaining Parmesan and the Fontina. Bake 15 to 20 minutes, or until beginning to lightly brown around the edges.
Sprinkle with additional rosemary before serving.
Notes
Originally posted FEB 2017.If not fire roasted tomatoes, regular canned tomatoes will work fine as a substitute. You can even add a pinch of smoked paprika to make up for it.