Vegetable Au Gratin

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This vegetable au gratin features crisp, tender vegetables smothered in a cheesy sauce, then topped with crispy breadcrumbs and parmesan. You’re going to love this easy side dish or main course that is ready in less than an hour! Kid-friendly & vegetarian.

Cheese-aholics rejoice! This roasted vegetable au gratin is jam-packed with perfectly cooked veggies in a decadent cheese sauce. Au gratin just means a dish is baked with breadcrumbs and cheese on top, which creates a golden brown, crispy exterior that complements the creamy, cheesy sauce underneath. It’s cozy, rich, and satisfying.

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Baked vegetable au gratin is my go-to dinner for busy weeknights. It may take 45 minutes to cook, but the prep work is a breeze! Make a cheese sauce, pour it over the veggies, top with breadcrumbs, and pop it in the oven. It’s that simple. Even my kids devour this vegetable au gratin casserole. Always a win!

This veg au gratin recipe is easy to customize too. It’s a nice “clean out your fridge” kind of recipe. Don’t let any leftover veggies go to waste, including frozen veggies. Enjoy as a perfect side dish or as a main meal with a side of garlic bread. I like to serve it for Sunday supper or at a dinner party.

👩‍🍳 Why This Recipe Works

• Full of nutrient-dense veggies like carrots, broccoli, and cauliflower!
• Rich and creamy with no heavy cream
• Crispy topping from the breadcrumbs
• Easy to make, but looks fancy and decadent
• Kid-friendly
• Great side dish or main meal
• Packed with delicious flavors
• Super customizable
• Best vegetables au gratin ever!

🥘 Ingredients

This vegetable au gratin recipe is made with simple ingredients found at your local grocery store. Here’s what you need.

• Butter: Fat is an essential part of any roux. A roux is a cooked mixture of flour and fat that works as a thickener, in this case for the cheese sauce. If you don’t have butter, olive oil makes a good swap.
• All-Purpose Flour: Flour thickens the milk mixture so it’s not runny.
• Low-Fat Milk: Milk is the base of the cheese sauce. If you don’t have low-fat milk, whole, reduced-fat, or plant-based milk works great too.
• Cheddar Cheese: I used cheddar for this veg au gratin, but any meltable grated cheese tastes delish. Try gouda, gruyere, Monterey jack, Italian blend, or a combination. If you don’t want lots of cheese, you can cut the amount in half.
• Seasoning: Salt enhances cheesy dishes and nutmeg adds a subtle sweetness.
• Vegetables: Broccoli, cauliflower, and carrots are a delicious combo, but any mix of vegetables work. Just remember to slice root vegetables like carrots and potatoes, so they cook through. Try adding green beans, zucchini, onion, potatoes, peas, parsnips, or spinach. Frozen veggies are also an easy and delicious option.
• Panko Breadcrumbs: For a golden brown crusty top. Whole-grain breadcrumbs are a great option for additional nutrients.
• Parmesan Cheese: A layer of parmesan cheese hardens as it bakes for a perfectly crisp golden brown top, and a totally delicious dish!

📖 Variations

Roasted cauliflower au gratin is easy to customize! Try one of these delicious variations.

• Make It Gluten-Free: Swap the all-purpose flour for a gluten-free all-purpose flour blend, and the bread crumbs for gluten-free breadcrumbs.
• Make It Vegan: Use a vegan bechamel sauce, vegan cheddar and vegan parmesan to make this recipe vegan friendly.
• Potato And Parsnip Gratin: Omit the veggies, and swap with sliced potatoes and parsnips.
• Root Vegetables Gratin: Omit the veggies, and swap with sliced root vegetables. Try onions, potatoes, parsnips, carrots, sweet potatoes, fennel, or yucca.
• Potato Courgette And Cheddar Gratin: Swap the veggies with sliced zucchini and potatoes. Salt the zucchini ahead of time to release any excess moisture, then pat dry.

🔪 Instructions

This broccoli cauliflower gratin is ready in less than an hour! Here’s how to make it with step-by-step pictures.

Preheat Oven, Melt Butter, Cook Roux: First, preheat the oven to 340 degrees Fahrenheit. Melt the butter in a medium saucepan over medium-low heat. Sprinkle in the flour and cook, continuously stirring, for about 2 minutes.

Add Milk & Cheese: Add the milk 1/4 cup at a time, stirring after each addition to ensure there’s no lumps. Once all the milk is added, cook for 2 more minutes to thicken. At this point you have a tasty bechamel sauce. Add the cheddar cheese, nutmeg, salt, and pepper to the pot. Stir for a couple more minutes until the cheese is melted and well combined. Remove cheese sauce from the heat.

Cover Veggies: In a large casserole dish, add the vegetables in an even layer. Pour on the creamy sauce, then stir until the veggies are evenly coated.

Top With Breadcrumbs: Sprinkle the breadcrumbs and parmesan cheese evenly over the veggies.

Bake Veg Au Gratin: Bake in the preheated oven for 30 to 35 minutes, until the cheese melts, the top has a golden crust, and the veggies are tender. If the veggies aren’t done, cover the pan with aluminum foil and cook 5 more minutes. Enjoy immediately!

❓ Recipe FAQs

💭 Expert Tips

• Avoid watery veggies: In general, you want to avoid vegetables that have a high water content. Root veggies and cruciferous veggies are great options. If you choose to use sliced zucchini, it’s best to salt it beforehand. This releases excess moisture which you can then pat dry. Doing this ensures the au gratin won’t get watery.
• For a lighter version: For a lighter dish with less fat, reduce the amount of cheese by half or use reduced-fat cheese.
• To ensure a perfect roux (bechamel sauce), the ratios of flour, butter and milk need to be exact, so make sure to measure carefully. If you have too much milk, your roux will be runny; but if you have too much flour, your roux will be thick and lumpy. You know the flour is cooked properly when it smells a little nutty after cooking in the butter for 1-2 minutes. Then, make sure to incorporate the milk slowly as you whisk to keep the sauce lump free!
• Cutting your veggies: Try to cut the vegetables into similar sizes so they cook evenly.

🍛 More Casserole Recipes to Try!

• Vegetarian Black Bean Casserole
• Vegan Sweet Potato Casserole
• Vegetarian Mexican Casserole
• Spaghetti Squash Casserole
• Taco Casserole
• Vegan Enchilada Casserole

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