Fennel and Prosciutto Gratin

From Fresh from the Farmers’ Market by Janet Fletcher (Chronicle Books).

• 1 tablespoon extra virgin olive oil
• 3/4 cup breadcrumbs made from day-old bread with crusts removed
• Kosher or sea salt
• 2 tablespoons unsalted butter, plus butter for the baking dish
• 2-1/2 tablespoons all-purpose flour
• 1 cup milk, or more if needed
• 1 cup homemade or canned low-sodium chicken broth
• 1 bay leaf
• 2 thyme sprigs
• 1 garlic clove, peeled and halved
• Freshly ground black pepper
• 1 pound fennel bulbs (weight after stalks are removed), about 2 medium bulbs
• 1 ounce thinly sliced prosciutto (2 to 3 slices)

Preheat oven to 425°F.

In a medium skillet, heat the olive oil over moderate heat. Add the breadcrumbs, stir to coat evenly with oil and cook, stirring often, until they are a deep golden-brown. Season with salt and set aside.

In a small saucepan, melt the 2 tablespoons butter over moderately low heat. Add the flour and whisk to blend. Cook 2 minutes, then add the 1 cup milk, broth, bay leaf, thyme sprig, halved garlic clove and salt and pepper to taste. Bring to a simmer, whisking. Adjust the heat to maintain a gentle simmer and cook 15 minutes, whisking often. Scrape the sides and bottom of the pan occasionally with a spatula. Add a little more milk if the béchamel gets too thick; it should be smooth and creamy, not thick or pasty.

Bring a medium pot of salted water to a boil over high heat. Add the fennel bulbs and boil for 10 minutes, then drain. Pat the bulbs dry, quarter them and remove the cores. Slice lengthwise into thin strips.

Generously butter a low-sided earthenware baking dish that measures approximately 12 by 7 inches. Arrange half the fennel in the baking dish in an even layer. Tear the prosciutto into shreds and arrange evenly over the fennel. Top with the remaining fennel in an even layer. Strain the béchamel over the fennel. Top with the breadcrumbs. Bake 20 minutes. If desired, broil briefly to brown the top. Cool 10 minutes before serving.

Serves 4