Baked cauliflower and broccoli cheese with a crunchy topping makes the perfect side dish to serve with a roast, or you could even eat it on its own for a light meal. The secret to a perfect cauliflower and broccoli cheese is baking the vegetables in the oven so they are guaranteed not to be soggy.

And I've got another secret for a crispy topping that I think you're going to love.
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Cauliflower and broccoli cheese au gratin
Baked cauliflower and broccoli cheese has to be one of my favourite side dishes to eat with a roast, but if it's not made properly you can end up with soggy cauliflower and broccoli and a thin, runny cheese sauce. I've found that the way around this is to roast the vegetables in the oven rather than steaming or boiling them first. This way they retain their 'crunch' because they don't absorb any additional water from the cooking process.
The cheese sauce is smooth and creamy with not a lump in sight. You can see how I make it further down this post. You need to use a nice sharp cheese such as cheddar to make the sauce. I like to combine the cheddar with grated Mozzarella cheese to give the cheese sauce a bit of 'stretch'. I just love stretchy cheese!
The topping itself is made with grated cheese mixed with Panko breadcrumbs, and then it's baked in the oven until the topping is crispy and golden. Mixing Panko breadcrumbs with grated cheese ensures that you get a really crunchy topping.
I've made this dish with both cauliflower and broccoli, but there's absolutely nothing stopping you from using either only cauliflower or broccoli. It will taste just as good with only one vegetable.
What you will need
Equipment
To make this cauliflower and broccoli cheese you will need a mixing bowl, a baking sheet and some baking parchment to line your baking sheet and make washing up easier.
You will also need a saucepan for making the cheese sauce, and a baking dish to make it all in. The baking dish should be large enough to hold all the vegetables plus the cheese sauce (approximately 8" x 8").
Ingredients
**You can get the complete list of ingredients and full instructions for making cauliflower and broccoli cheese on the printable recipe card at the end of this post**
Cauliflower and broccoli - you will need approximately 1 cup of vegetables per person. The cauliflower and broccoli should be separated into smallish florets. Cauliflower is heavier than broccoli, so 2 cups of cauliflower weighs around 300 grams whereas 2 cups of broccoli only weighs around 200 grams.
Oil - this is sunflower oil or any other neutral-flavoured oil such as canola. It is mixed with the vegetables along with salt and pepper before they are roasted.
Milk - you can use either full-fat or semi-skimmed milk.
Butter - salted or unsalted. If you use salted butter you may not need to add any additional salt to the sauce.
Flour - used to thicken the sauce.
Dijon mustard - to add additional flavour. If you don't like mustard you can leave it out.
Cheese - you need a cheese that melts easily such as cheddar. I like to use a mixture of cheddar and mozzarella.
Panko breadcrumbs - these are mixed with some of the cheese to form the crispy topping. For those of you who don't know, Pando breadcrumbs are made from the crumbs of light Japanese bread. They make a crispier coating than normal breadcrumbs as they don't tend to absorb oil. You can substitute it with regular breadcrumbs if you prefer.
How to make it
Prepare the cauliflower and broccoli
Place the cauliflower and broccoli florets into a mixing bowl, pour in the oil and sprinkle with the salt and pepper. Mix well to combine and then spread the florets onto a baking tray lined with baking parchment.
Bake the vegetables in a preheated oven (200C / 400F) for 12 to 15 minutes until they start to brown.
The florets should be fork-tender. If they seem too hard, leave them for another minute or two. Remember, the vegetables will continue to cook once they go back into the oven with the sauce.
Make the cheese sauce
While the vegetables are roasting, you can get on with making the cheese sauce.
Melt the butter in a saucepan and then stir in the flour. Take care to remove any lumps of flour.
Add the milk and the mustard and stir over gentle heat until the mixture thickens. It should pour slowly from the spoon.
Stir in the cheese and continue to heat until the cheese has melted.
Taste the sauce and season with salt and black pepper to taste.
Assemble and bake
Transfer the roasted cauliflower and broccoli into a baking dish.
Pour the cheese sauce over the vegetables.
Combine grated cheese with Panko breadcrumbs.
Sprinkle the grated cheese on top of the sauce.
Bake the cauliflower and broccoli cheese for 15 minutes (200C / 400F) until the cheese is melted and the breadcrumbs are golden.
To let the cheese and breadcrumb topping brown more easily you may like to add a few dots of butter before baking the dish in the oven. I think there is enough butter in the sauce, so I don't bother doing this.
You may also like to sprinkle chopped chives on top when the dish comes out of the oven, but this is totally optional.
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Serving suggestion
I like to serve baked cauliflower and broccoli cheese as a side dish with a roast, alongside a dish of mashed potatoes and lots of gravy.
FAQ
Technically the answer is yes. However, freezing the cauliflower and broccoli would cause the structure of the vegetables to change, and they would become watery and mushy once defrosted, so I wouldn't recommend it.
Yes, you can prepare this dish up to 2 days in advance. Cover the assembled dish and leave it in the refrigerator until you are ready to bake it, then follow the baking instructions above.
You could also roast the vegetables and prepare the cheese sauce, then store them in separate containers in the refrigerator. If you do this you may find that the cheese sauce has thickened in the refrigerator and you may need to warm it in a saucepan or in the microwave so that you can pour it more easily over the vegetables.
Leftovers can also be stored in the refrigerator for 2 days and reheated in the microwave.
Au gratin is a French term and simply means 'by grating'. So any dish prepared 'au gratin' just means it has a topping of something that has been grated (normally cheese).
Save for later
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Related recipes
If you enjoyed this cauliflower and broccoli au gratin you may also like to try some of my other vegetable side dishes. Here are a few you may enjoy:
📋The recipe
Cauliflower and broccoli cheese
(Click the stars to rate this recipe)
Equipment
- 1 Mixing bowl
- 1 Saucepan
- 1 Baking sheet
- Baking parchment
- 1 8" x 8" Baking dish approximate size
Ingredients
Vegetables
- 2 cups cauliflower (about 300 grams) broken into florets
- 2 cups broccoli (about 200 grams) broken into florets
- 2 tablespoons sunflower oil
- salt and black pepper to taste
Cheese sauce
- 2 cups / 480 ml milk full-fat or semi-skimmed
- 2 ounces / 60 grams butter
- 4 tablespoons / 40 grams plain all-purpose flour
- 1 teaspoon Dijon mustard or more to taste
- 1 cup / 125 grams grated cheddar cheese
- salt and black pepper to taste
Cheesy topping
- ½ cup / 60 grams grated cheddar cheese
- ½ cup / 60 grams Panko breadcrumbs or normal breadcrumbs
Instructions
Vegetables
- Preheat the oven to 200°C / 400°F
- Break the cauliflower and broccoli into florets and put them into a mixing bowl with the oil, salt and black pepper.2 cups cauliflower (about 300 grams), 2 cups broccoli (about 200 grams), 2 tablespoons sunflower oil, salt and black pepper to taste
- Mix well to combine, then spread the vegetables on a baking tray lined with baking parchment.
- Bake the vegetables in a preheated oven (200C / 400F) for 12 to 15 minutes until they start to brown.
Cheese sauce
- Melt the butter in a saucepan and then stir in the flour. Take care to remove any lumps of flour.2 ounces / 60 grams butter, 4 tablespoons / 40 grams plain all-purpose flour
- Add the milk and the mustard and stir over a gentle heat until the mixture thickens. It should pour slowly from the spoon.2 cups / 480 ml milk, 1 teaspoon Dijon mustard
- Stir in the cheese and continue to heat until the cheese has melted.1 cup / 125 grams grated cheddar cheese
- Taste the sauce and season with salt and black pepper to taste.salt and black pepper to taste
Assemble and bake
- Transfer the roasted cauliflower and broccoli into a baking dish.
- Pour the cheese sauce over the vegetables.
- Combine grated cheese with Panko breadcrumbs in a small dish and then sprinkle it over the cheese sauce.½ cup / 60 grams grated cheddar cheese, ½ cup / 60 grams Panko breadcrumbs
- Bake the cauliflower and broccoli cheese for 15 minutes (200C / 400F) until the cheese is melted and the breadcrumbs are golden.
- Serve hot as a side dish with a roast.
Notes
Nutrition
I am not a nutritionist. The nutrition information has been calculated using an on-line calculator, and is intended for information and guidance purposes only. If the nutrition information is important to you, you should consider calculating it yourself, using your preferred tool.
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