Cheesy Broccoli Cauliflower Casserole (Vegetable Au Gratin)
Enhance any meal or holiday table with this easy Cheesy Broccoli Cauliflower Casserole, a.k .a. Vegetable Au Gratin. Not just for the holidays, this makes a wonderful side dish year-round. It’s easy to make and perfect for adjusting to dietary needs, like keto, dairy-free and gluten-free.
Preheat the oven to 375° F (190° C). Lightly coat an 8x8, 9x9 or gratin baking dish with oil or butter.
Add 1-2 inches of water into a large pot fitted with a steamer basket. Bring the water to a boil. Carefully add the broccoli and cauliflower, cover, and simmer until just crisp tender, about 5 minutes. Remove the basket from the pot and allow it to drain.
Heat a medium saucepan or skillet to medium heat. Add the olive oil, allow it to warm a bit, and then add the onion and saute until translucent, about 5 minutes. Add the garlic and stir until fragrant, 30 seconds.
Add the flour (or alternative) and stir constantly, until the mixture turns golden and thick.
Slowly add the half and half, about ½ cup at a time, stirring constantly, adding more as it thickens.
Once the sauce has thickened, lower the heat, and add the cheeses in small batches and stir until melted.
Add the nutmeg and stir to combine. Add salt and pepper to taste. I used ½ teaspoon of each.
Add the steamed broccoli and cauliflower to the sauce and stir to coat. Then pour the mixture into the prepared baking dish.
Combine the melted butter, breadcrumbs and 2 tablespoons of parmesan cheese in a small bowl. Sprinkle over the top of the casserole.
Bake for 25 minutes until bubbly and top is slightly golden, serve immediately.
Notes
Buy the blocks of white cheddar, Swiss, and parmesan cheese and grate yourself. Pre-shredded contains additives, and it doesn’t melt as nicely. ● Fresh broccoli and cauliflower will give the best texture in this dish. ● Whole milk can be substituted for half and half. You can also use 2% or skim milk, but it will be less creamy and rich. ● Don’t overcook the veggies when steaming; they will cook more in the oven. Overcooking will result in mushy vegetables. ● Add cooked chicken breast to the sauce with the vegetables to make this a main dish. ● Broccoli and cauliflower can be bland vegetables; taste and add more seasoning if necessary.Gluten-Free Broccoli and Cauliflower Casserole | Use a gluten-free brand of panko breadcrumbs and a gluten-free flour alternative in your sauce to make the dish gluten-free. Grate your own cheese, as pre-shredded packs have additives that often contain gluten. That is it!Low-Carb Broccoli and Cauliflower Bake | Substitute almond or coconut flour for the flour to make the dish low-carb. Skip the panko breadcrumbs, or toss some pork rind crumbs with melted butter and sprinkle on top.Add Protein | Add cooked chicken breast, turkey, rotisserie chicken, diced ham, or bacon to the sauce with the vegetables to make this a main dish. Leftover turkey from the holidays works, too!Vegan Vegetable Au Gratin | All you need to do for a vegan or dairy-free version is replace the cheese, cream, and butter with your favorite plant-based products.