"Served bubbling hot in a savory garlic and cheesy cream sauce, this side dish can take the center stage if paired with a risotto or semolina gnocchi. In the autumn, this dish makes a regular appearance at our dinner table as we harvest it straight from the garden."
Place a steamer insert into a saucepan and fill with water to just below the bottom of the steamer. Bring water to a boil. Add cauliflower, cover, and steam until crisp tender, 2 to 3 minutes. Drain in a colander and immediately immerse in ice water to stop the cooking process. Drain well.
Preheat oven to 350 degrees F (175 degrees C).
Melt butter in a saucepan over low heat. Add garlic; cook and stir until soft and fragrant, about 1 minute. Whisk in flour until smooth, 1 to 2 minutes. Pour in milk and cream. Increase heat to medium and simmer, whisking frequently, until sauce starts to thicken, about 5 minutes. Bring to a boil; continue to cook until sauce is thick, about 5 minutes.
Stir Parmesan cheese, fontina cheese, salt, nutmeg, and white pepper into sauce. Cook, whisking vigorously, until cheese is melted into the sauce, about 1 minute. Remove from heat.
Spread 1 cup of sauce on the bottom of a baking dish. Arrange cauliflower on top. Drizzle remaining sauce over the cauliflower, coating each floret.
Bake in the preheated oven until bubbling and lightly browned on top, about 10 minutes.