Cauliflower, Leek and Fontina Gratin

This easy gratin starts with roasted cauliflower and sautéed leeks, then pairs with fontina cheese, cream, and fresh thyme. It's comforting and delicious, but beware, it's also rich. So don't eat the whole thing yourself!  

Serves 4 as a side

• 2 cups sliced leeks
• 1 pound small cauliflower florets (about 6 cups, about 1 small head)*
• 3 tablespoons extra-virgin olive oil, more for pan
• Kosher salt
• 2 tablespoons unsalted butter
• 1 ½ teaspoons chopped fresh thyme
• Fresh pepper
• 1 cup coarsely grated Fontina
• 1 cup heavy cream

1. Heat the oven to 450 degrees. Line a heavy-duty rimmed sheet pan with parchment paper. (Line first with aluminum foil for easier clean-up.)
 
2. Put the leeks in a bowl and cover with tepid water.

3. Rub a little olive oil all over the inside of a small (about 1 ½ quarts volume) shallow gratin or baking dish. (Mine is oval, about 9 inches long.)

4. In a mixing bowl, toss the cauliflower with the 3 tablespoons oil and ¾ teaspoon kosher salt. Spread on the baking sheet and roast, turning the pan once and flipping once if you like, until the cauliflower all has some nice browning on the undersides and on spots and is tender, about 22 minutes.

5. Meanwhile, in a medium (10-inch) nonstick skillet, melt the butter over medium heat. Transfer the leeks to the pan, using your hands to lift them out of the water so that some water will still be clinging to them. Season with ½ teaspoon salt. Cook the leeks, stirring, until the pan is dry and the leeks are softened and beginning to brown, about 10 minutes. Reduce the heat to medium low; add the thyme and a few grinds of fresh pepper to the pan and stir. Add the heavy cream and let it bubble up for a few seconds. Remove the pan from the heat.

6. Arrange the roasted cauliflower in the baking dish. Arrange ¾ of the fontina over it. Pour and scrape the leek-cream mixture over the cauliflower. Gently poke or stir a few of the cauliflower so they come to the surface and then smooth the top. Sprinkle with the remaining fontina.

7. Cook until golden brown and the bubbling liquids have reduced a bit, leaving a thin brown ring around the edge of the pan, about 20 minutes.  

*For the best browning, cut florets through the middle so that they have one flat side. Arrange the flat sides down on the baking sheet and they will get nicely browned.