Cheddar Broccoli & Cauliflower Gratin Side Dish

Consider this gratin a grown-up version of the quintessential vegetable comfort food: cheese sauce-smothered broccoli (cue childhood flashbacks). While its got all the coziness of the classic, it tastes rather fancy—quite the vegetable glow-up.

If you’re new to gratins, it’s a cooking technique where a dish is topped with a crust, typically made of breadcrumbs, cheese, or a mix of both. This is then baked or broiled until gloriously golden and crisp. You can use it over potatoes (the most famous being the traditional gratin dauphinois, which features heavy cream), vegetables, and even seafood!

My recipe is a vegetable gratin (surprise, surprise). The vegetables are tossed in a béchamel sauce—a white sauce and one of the mother sauces of classic French cuisine—and sprinkled with an insanely good breadcrumb herb crust. Using béchamel over cream adds a lighter touch, while still providing a creamy texture. As a Registered Nutritionist, I reckon it’s a delicious way to dress up cauliflower and broccoli—truly a dish to nourish and tempt🥦.

Gather Ingredients

• Broccoli and cauliflower. We’re after 600g of florets—one medium broccoli and half a medium cauliflower should do the trick. You can also use part of stalks, they’re edible (it’ll reduce food waste too, win-win!)—just steer clear of anything tough or fibrous.
• Aromatics. Sautéed brown onion and garlic are an easy way to add great flavour depth (alongside getting more veg in!).
• Cheese. Sharp cheddar and parmesan cheese to flavor the béchamel, and parmesan in the crust for a nutty flavour and crisp texture.
• Wholemeal breadcrumbs. The base of our crisp golden brown crust. Using wholemeal breadcrumbs over white also gives rustic vibe (and a smidge more dietary fibre🤙).
• Fresh rosemary. For great flavour and a gorgeous aroma.

You’ll also need the basics: butter, flour and milk for our béchamel; olive oil to help the gratin topping become crisp; and salt and pepper to season it all to perfection.

Step-by-Step: Baked Vegetable Gratin

Kitchen Tips

Béchamel sauces become easier to make with practice—it can take a few attempts to know what to look out for at each stage. Below are tips to get you acquainted:

• Warm the milk. Start with warm milk for the smoothest sauce. Cold milk slows down the process (it should only take 10-15 minutes to make the sauce, start to finish) and increase the chance of lumps. A quick zap in the microwave is all it takes—this small step makes a big difference!
• Cook the roux (butter + flour). Give the roux a minute or two to cook. It should stay pale, with just a hint of golden colour. This step removes that raw flour taste, but don’t let it brown—it’s béchamel, not a gravy base!
• Mind the heat. Medium heat is your friend. Too low, and the sauce takes forever to thicken; too high, and you risk scorching the bottom. Dial up the heat a little, if needed, to hurry it along, but don’t keep it high for long or you’ll risk scotching it.
• Whisk, whisk, whisk. For a silky sauce, whisk constantly as you slowly add the milk. Otherwise the flour in the roux can clump together, and those pesky lumps are difficult to dissolve​.
• Switch between tools. Start with a wooden spoon for making the roux, then, switch to a whisk when adding the milk. Once the sauce thickens, go back to the spoon to stir and scrape the bottom of the pan to prevent sticking.

How do you know your Béchamel sauce is ready? It should have a smooth, velvety texture that coats the back of a spoon. To check, dip a spoon into the sauce and run your finger through it on the back. If the line stays clear and the sauce doesn’t run, it’s thickened! Otherwise, it should also be thick enough to hold its shape slightly when poured, and taste rich and creamy, without any raw flour flavour.