Broccoli-Cauliflower Gratin with a grownup Brie and cheddar cheese sauce is a side dish everyone loves to see on the table at dinnertime.
Leftovers create an amazing creamy soup too!
Easy Vegetable Side Dish
Broccoli and Cauliflower Gratin is an easy recipe to customize to your own taste. Roast or steam the vegetables and select any favorite cheese with good melting properties from the list below.
You’ll also find simple substitutes for making it gluten-free with sweet rice flour while maintaining the integrity and quality of the dish.
How to Make a Great Cheese Sauce
- Know your cheese. The selection of cheese is important for melting properties and flavor. We choose Brie to deliver a creamy, luxurious texture with extra-sharp cheddar and Parmesan to bring some punch.
⇒ Gruyere, Gouda, Fontina, Asiago, Provolone, Swiss, Taleggio, or Reblochon-Style cheese are all terrific choices for an amazing cheese sauce. Mozzarella can be used but is challenging to keep smooth and not stringy. Use only pure, real cheese, and never cheese foods.
- Balance with acid and a touch of spice. An acid like Dijon paired with a tiny bit of spice from cayenne brings a welcome contrast to heavier foods and sauces.
- Grate the cheese yourself. Pre-grated cheese will often have a coating of cellulose to keep it from sticking together in the package. This can inhibit a cohesive melting or leave the sauce slightly gritty. Grate the cheese from a block using a small hole grater—the more finely grated it is, the easier it will melt.
- Go low and slow. Keep the heat low enough so the sauce forms large bubbles that pop slowly, like scattered raindrops. Stir constantly to keep everything smooth and silky.
- Don’t overcook cheese sauce. The proteins in cheese will change the consistency if overheated. Bring the cheese to room temperature so it isn’t cold when adding it to the sauce. After the sauce has thickened, remove the sauce from heat before adding the cheese. The heat from the sauce will melt the cheese as you stir it in.
Just in case the phone rings or phone notifications distract (it happens), here’s an excellent resource for TIPS to save a broken sauce: Taste of Home, How to Save a Broken Sauce
Broccoli & Cauliflower Gratin Step by Step
- Roast vegetables at 400°F for 8-10 minutes.
- Make the cheese sauce by heating the butter in a saucepan until bubbly. Whisk in flour and cook on medium-low for 3-4 minutes. Reduce heat to low and whisk in milk, Dijon, and a pinch of cayenne; barely simmer on low about 5 minutes. Remove from heat and stir-in brie and cheddar cheese, continuing to stir until cheese is melted.
- Pour the sauce over the vegetables and sprinkle with Parmesan and bread crumbs. Spray crumbs lightly with cooking spray.
- Broil for 10 minutes until the cheese is bubbly and topping is lightly browned in spots.
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Gratin One Night, Soup for Lunch
My advice is to make more than you think you’ll need because it makes a fantastic cream soup for lunches. To make soup with leftovers, simply place leftovers in a food processor or use an immersion blender to puree until smooth.
Gently warm in a saucepan and thin with chicken broth or water to the desired consistency. Garnish with fresh chopped scallions or chives to serve.
More Vegetable Side Dish Recipes Your Family Will Love
- Tuscan Roasted Broccoli
- Roasted Vegetable Medley
- Vegetable Tian
- Grilled Asparagus with Cotija Cheese
- Skillet Roasted Cauliflower Mash
- Grilled Cabbage with Classic Caesar Dressing
- Roasted Brussels Sprouts with Garlic Aioli
- Roasted Asparagus with Caramelized Onions and Blue Cheese
- 16 ounces cauliflower , cut into bite-sized pieces slightly smaller than the broccoli
- 16 ounces broccoli cut into bite-sized pieces
- Sea salt and freshly ground pepper
- 2 1/2 tablespoons butter
- 2 tablespoons white whole wheat flour or sweet rice flour for gluten-free
- 1 cup whole milk plus more to thin sauce as desired
- 1/2 teaspoon Dijon mustard or 1 teaspoon lemon juice
- Pinch cayenne pepper
- 1 cup Brie cheese cut into small cubes
- 3/4 cup grated extra-sharp cheddar cheese
- 1/2 cup grated Parmesan cheese
- 1/2 cup panko bread crumbs or gluten-free Panko crumbs
- pinch ground white pepper
- Olive oil cooking spray or duck fat spray
- 9×13 Broiler-safe baking dish
- Season cauliflower and broccoli with salt and pepper. Roast in a 400°F oven for 8-10 minutes -OR- steam in a large skillet with a lid and 1/3 cup water over medium heat for 5-6 minutes until crisp-tender. (Add more water, if needed)
- While the vegetables are cooking, melt 2 1/2 tablespoons butter In a medium saucepan. Use this melted butter to brush in the baking dish and then transfer vegetables to the baking pan in a single layer. Heat the broiler and position rack 8-10 inches from the heating element. Note: If you don’t have a broiler-safe dish, bake on convection bake at 400°F – this will brown the top more efficiently without overcooking the cheese sauce.
- Return the remaining butter to the stove and heat until bubbly. Add 2 tablespoons flour and whisk over medium heat until bubbly. Continue to cook on medium-low for 3-4 minutes to incorporate the flour fully.
- Reduce heat to low and whisk in 1 cup of milk, 1/2 teaspoon Dijon, and a pinch of cayenne; continue to stir and gently simmer on low about 5 minutes or until sauce thickens. Remove from heat and stir-in 1 cup cubed Brie and 3/4 cup cheddar cheese, continuing to stir until cheese is melted. Taste and season with salt and pepper.
- Pour the sauce over the vegetables and sprinkle with Parmesan and bread crumbs. Spray crumbs lightly with cooking spray and broil for 10 minutes (depending on broiler – watch closely) until the cheese is bubbly and topping is lightly browned in spots.
If you try this or any other recipe on the blog, please rate the recipe and let me know how it went for you in the comments below. It makes my day to hear from you!