We prefer smaller tomatoes, such as Campari or Kumato (sometimes labeled “cocktail tomatoes”); other tomato varieties, cut into rough 1- to 2-inch pieces, will also work. Shred the fontina on the large holes of a box grater and grate the Parmesan cheese on a rasp-style grater. Do not use pre-grated Parmesan here; it may contain additives that can affect the sauce’s texture. Serve with crusty bread, toasted or grilled.

FOR THE TOMATO SALAD: Toss cornichons and brine, oil, shallot, and ¼ teaspoon table salt together in bowl; set aside. Toss tomatoes gently with pepper and remaining ½ teaspoon table salt.

FOR THE CHEESE SAUCE: Bring cream to boil in large saucepan over medium-high heat. Reduce heat to medium-low and simmer, whisking occasionally, until cream is reduced to 1½ cups, 15 to 18 minutes. (If mixture begins to boil over, briefly remove saucepan from heat; adjust heat as needed to maintain consistent simmer.) Off heat, add fontina, Parmesan, and salt and whisk until cheeses are fully melted and sauce is smooth, about 30 seconds.)

Immediately transfer cheese sauce to large platter and spread into even layer (sauce may appear thin at first; it will thicken quickly as it cools). Arrange tomatoes in even layer over cheese sauce. Drizzle cornichon dressing over tomatoes. Sprinkle with thyme and flake sea salt. Serve.

Getting the Fonduta Just Right