Method

• Melt butter on medium heat in a medium sized saucepan. Add the sliced leeks and gently cook until completely softened, about 8 to 10 minutes.
• While the leeks are cooking, place cauliflower florets in a steamer basket in a saucepan over an inch of water. Bring water to a boil, cover, and steam the cauliflower for 3 to 4 minutes.
• Add 2 tablespoons of flour to the leeks and butter. Stir and let cook for a minute or two. Slowly add the milk, stirring as you add it to break up any lumps.
• Once the sauce is thick enough to coat the back of a spoon, stir in 3 ounces of the shredded cheese, thyme, nutmeg, and salt.
• Preheat the oven to 400°F.
• Spread a teaspoon of butter over the insides of a 2-quart gratin dish. Place the lightly steamed cauliflower florets in an even layer in the dish. Pour the leek and cheese sauce over the cauliflower. Top with remaining cheese.
• Bake for 25 minutes.
• While the gratin is baking, melt 1 tablespoon of butter in a small sauté pan on medium high heat. Add the fresh breadcrumbs and toast in the melted butter for 4 to 5 minutes, until lightly browned.
• After the gratin has baked for 25 minutes, remove it from the oven. Sprinkle toasted breadcrumbs over the top and return to the oven. Bake for 5 more minutes.