Step 1

Preheat the oven to 375 F.

Step 2

Bring a large pot of water to a boil. Add 1 teaspoon of salt, cauliflower florets and potatoes and cook on a medium heat for 7 minutes. Drain.

Step 3

In a medium saucepan over medium heat, melt 2 tablespoons of butter, add flour and whisk to combine. Add warm milk, stirring constantly until the sauce thickens.

Step 4

Remove pan from the heat. Add the remaining 1/4 teaspoon of salt, pepper, 1/4 cup of Gruyere cheese, Parmesan and nutmeg. Give it a taste and add more salt if needed.

Step 5

Transfer cauliflower and potatoes into the 8 by 11 inches baking dish. Cover with a sauce and carefully mix to combine the ingredients.

Step 6

Sprinkle Panko and the remaining 1/4 cup of Gruyere on top of the gratin and drizzle with 2 tablespoon of melted butter.

Step 7

Bake for 25 to 30 minutes until vegetables are tender.Turn on the broiler and bake for 2-3 minutes until top of the gratin is golden brown.

Step 8

Serve immediately.