Instructions:

Preheat oven to 400° F.

Heat oil in a large saute pan set over medium heat. Add onions to the hot olive oil and cook for 5-6 minutes, until beginning to soften and become translucent. Stir in garlic, tomato paste, and 1 tsp of salt and cook for another 3-4 minutes.

Stir in herbs, chopped tomatoes, and the remaining teaspoon of salt and bring to a low simmer. Simmer for 15-20 minutes, until mixture is thick and chunky and almost all of the tomato liquid has evaporated.

When you are ready to assemble the gratin, place half of the tomato and onion mixture in an even layer in the bottom of your baking dish. Arrange half the potato and tomato slices in an even layer on top of the tomato mixture, then top with half of the grated Fontina cheese.

Repeat this layering one more time with the remaining tomato onion mixture, followed by the sliced potatoes and tomatoes, and top with the remaining cheese.

Bake uncovered for 50-55 minutes, until potatoes are completely cooked through and most of the liquid has evaporated. If the gratin needs a little longer baking time, but the top is beginning to brown quickly, cover it with foil while baking.

When the gratin is fully cooked, let cool slightly before scooping or slicing. Serve hot.