This broccoli au gratin (aka cheesy broccoli casserole) is a delicious side dish that consists of lightly charred broccoli smothered in a creamy cheesy sauce, then baked until golden brown with crispy, buttery breadcrumbs on top. It’s a perfect vegetable side dish that even broccoli haters will love.
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Ingredients
This broccoli gratin is made with some very simple, classic ingredients that should be available at your local store. Ingredient quantities can be found in the recipe card at the bottom of this post.
- Broccoli: I used 3 small heads of broccoli to get the 5 cups needed for this recipe. It gets cut up into pretty small bite-sized pieces, discarding most of the stem.
- Shallot and garlic: to bring a more mild allium flavor that helps cut the decadence of the cheese sauce.
- Butter: unsalted butter to make the roux which is the base of the cheese sauce. It's also used to sauté the garlic and shallot.
- Flour: standard all purpose flour gets mixed with the butter to make the roux.
- Whole milk: the base of the cheese sauce, it gets perfectly thick without feeling too heavy.
- Gruyere cheese: classic gratin cheese, gruyere is a Swiss cows-milk cheese that’s on the milder side and slightly nutty and sweet. As it ages, the flavor becomes bolder and more complex. It's perfect for making a creamy sauce.
- Parmesan cheese: adds a slightly salty sharpness to the cheese sauce.
- Panko breadcrumbs: Japanese breadcrumbs – they are big flaky clusters that are a great crunchy topping.
- Olive oil: for drizzling on the broccoli before it's baked.
Step by step instructions
This broccoli gratin is made simply by par-baking fresh broccoli florets, tossing it with shallots, garlic, and a creamy homemade cheese sauce, then topped with breadcrumbs and baked until golden brown.
1. Roast the broccoli. Lay the broccoli out on a sheet tray in a single layer, drizzle with olive oil, kosher salt, and black pepper. Roast for 10 minutes until some tips start to get charred.
2. Sauté shallot and garlic. While the broccoli is roasting, warm 1 tablespoon olive oil over medium heat in a medium saucepan. Add the chopped shallot and garlic and sauté until soft, about 5 minutes. Transfer to a large mixing bowl.
3. Make a roux. Wipe out the pot and set it back over medium heat. Add the butter and let it melt, then sprinkle flour overtop. Whisk until the butter absorbs the flour and cook for 1-2 minutes to let the raw flour taste cook out. You should have a very pale roux.
4. Add the milk. While whisking constantly, slowly pour the milk into the roux. Bring to a light simmer and cook for 4-5 minutes until it has thickened slightly and coats the back of a spoon.
5. Add the cheese. Turn the heat to low and stir in the gruyere and parmesan cheeses until fully combined. Season with kosher salt and black pepper.
6. Combine the broccoli, shallot and garlic, and creamy bechamel sauce sauce. Add the broccoli and cheese sauce to the large bowl with garlic and shallots. Mix until combined then transfer to a greased baking dish (or au gratin dish if you have it).
7. Mix the butter and panko. In a small bowl, combine the melted butter and panko breadcrumbs.
8. Top with panko. Sprinkle the buttery breadcrumbs all over top of the broccoli.
9. Bake. Bake in the oven for 25 minutes until golden and bubbly.
What is au gratin?
Au gratin means a dish that is topped with breadcrumbs or cheese and then baked until golden.
Ingredient substitutions
- Substitute cauliflower instead of broccoli if you’d like!
- Other than gruyere, you could use sharp cheddar cheese, Swiss cheese, or gouda cheese.
- You can use frozen broccoli, do the roasting step straight from frozen.
- Add some herbs into the cheese sauce such as fresh sage or fresh thyme.
- Use garlic powder in place of fresh garlic – use ¼ tsp!
- Use onion powder in place of shallot – use ½ tsp!
Tips and tricks
Check out the tips and tricks below to help make sure you nail this cheesy broccoli au gratin recipe.
- Add the cheese on low heat so it blends more seamlessly into the sauce.
- If you want a nuttier flavor, cook the roux until it becomes a more golden color.
- If for some reason you’re not getting a nice golden brown crispy top, try broiling the dish for a few minutes. But keep your eye on it, as the broiler can quickly go from golden brown to burnt.
- If your oven is occupied, instead of roasting the broccoli in the beginning of the recipe you can blanch it or use a vegetable steamer to steam it. The goal is to get it at least 75% cooked before mixing it with the cheese sauce.
- Use a food processor to chop the broccoli into small florets – but be careful to not completely pulverize them.
- If your baking dish is filled to the brim, I recommend placing it on a baking sheet before putting it in the oven to catch any potential overflow.
- Along with the breadcrumbs on top, feel free to sprinkle additional cheese on top as well – I'd do cheese, then breadcrumbs.
Storage and reheating
- To store this dish, allow it to come to room temperature and transfer to an airtight container. Store in the fridge for up to 4 days.
- To reheat this dish, either warm it in the microwave for a minute or two, or put it back in the oven at 350°F until warmed through, about 10-15 minutes.
Make ahead instructions
This is a great broccoli side dish and making it ahead can really add to the ease of it, especially on a busy night or holiday. It can be prepared up to 2 days in advance. To prepare it in advance, make the recipe up until mixing the butter with breadcrumbs and baking. Then about 30 minutes before you want to eat it, mix together the breadcrumbs with the butter, sprinkle them over the dish, then bake.
FAQs
I have never tried that before, but if you’d like to, here’s a vegan cheese sauce that looks great.
Yes! You’ll need to make two swaps – first being the breadcrumbs. Either skip the breadcrumbs and instead top the dish with more cheese, or try to find gluten free breadcrumbs. You’ll also need to use gluten free 1:1 flour instead of all purpose flour.
More side dish recipes
📖 Recipe
Broccoli Au Gratin
Ingredients
Roasted broccoli
- 5 cups broccoli cut into small pieces
- 1 tablespoon olive oil
- 1 teaspoon kosher salt
- ½ teaspoon black pepper
Shallot & garlic mixture
- 1 tablespoon olive oil
- 1 shallot chopped
- 2 cloves garlic chopped
Cheese sauce
- 2 tablespoon unsalted butter
- 2 tablespoon all purpose flour
- 2 cups whole milk
- 1 cup grated gruyere cheese
- ¼ cup grated parmesan cheese
- 1 teaspoon kosher salt
- ½ teaspoon black pepper
Panko topping
- ½ cup panko breadcrumbs
- 1 tablespoon unsalted butter
Instructions
- Preheat your oven to 425℉.
- Lay the broccoli out on a sheet tray in a single layer, drizzle with olive oil, kosher salt, and black pepper. Roast for 10 minutes until some tips start to get charred.
- While the broccoli is roasting, warm 1 tablespoon olive oil over medium heat in a medium saucepan. Add the chopped shallot and garlic and sauté until soft, about 5 minutes. Transfer to a large mixing bowl.
- Wipe out the pot and set it back over medium heat. Add the butter and let it melt, then sprinkle flour overtop. Whisk until the butter absorbs the flour and cook for 1-2 minutes to let the raw flour taste cook out. You should have a very pale roux.
- While whisking constantly, slowly pour the milk into the roux. Bring to a light simmer and cook for 4-5 minutes until it has thickened slightly and coats the back of a spoon.
- Turn the heat to low and stir in the gruyere and parmesan cheeses until fully combined. Season with kosher salt and black pepper.
- Add the broccoli and cheese sauce to the large bowl with garlic and shallots. Mix until combined then transfer to a greased baking dish (or au gratin dish if you have it).
- In a small bowl, combine the melted butter and panko breadcrumbs.
- Sprinkle the buttery breadcrumbs all over top of the broccoli.
- Bake in the 425°F oven for 25 minutes until golden and bubbly.
Lindsey says
I've always loved au gratin potatoes, but the garlic butter herb sauce took it to the next level. Both my husband and I ate the entire pan! It's soo comforting and flavorful.
Haley says
Thank you! I'm glad you loved it! I agree, the garlic herb butter really is delicious.
Jean MacDonald says
Excellent AU gratin potatoes. Love the two cheeses! Delicious
Haley says
Thank you so much! Glad you loved them!