Deeply flavorful roasted garlic and a crispy rosemary breadcrumb topping takes this creamy cauliflower au gratin to the next level!
The annual Thanksgiving side palooza is in full swing! I’ve got a couple more incredible side dishes yet to come this month before turkey day, but for now it’s all eyes on the almighty cauliflower.
And it really is mighty today, lemme tell you. Cauliflower gratin featuring the creamiest roasted garlic sauce, all the tender cauliflower, a mountain of crispy rosemary breadcrumbs, and did I mention ROASTED GARLIC??
To be honest, I’m not sure if you’ll have room for much else on Thanksgiving if this gratin is on the menu.
You should know by now that I’m no fan of spending the holidays solely in the kitchen so naturally, this is one of those side dishes that has a host of make-ahead options! Keep reading for all the details.
This Cauliflower Gratin features…
- Nutty smashed roasted garlic
- Tender roasted cauliflower in a creamy Parmesan sauce
- Crispy rosemary breadcrumbs baked on top
Making the Cauliflower Gratin
(scroll down to the bottom of the post for the full recipe)
Ingredients You Will Need
- Garlic
- Olive oil
- Cauliflower
- Unsalted butter
- All-purpose flour
- 2% or skim milk
- Heavy whipping cream
- Parmesan cheese
- Panko breadcrumbs
- Rosemary
How To Roast Garlic
Roasted garlic is so easy to make and instantly elevates any savory dish! All you need is a full head of garlic, a little olive oil, salt + pepper, and tin foil for wrapping garlic.
Slice the top off the head of garlic to expose the cloves and lightly top with olive oil, salt, and pepper. Wrap the garlic well in tin foil and roast at 400F 50-55 minutes until the garlic is completely soft and lightly browned.
Tips for Perfect Cauliflower Gratin
- Finish roasting garlic alongside cauliflower – to save on roast time, I like starting the garlic and then adding cauliflower to the pan about 35 minutes into roasting so they both finish cooking at the same time.
- Roast cauliflower until crisp-tender – this should take about 15-20 minutes at 400F. You want the cauliflower just a little on the crisp side since it will finish cooking later in the sauce.
- Make a roux – a roux is equal parts butter and flour and it is the base to your sauce. Cook the roux over medium heat, whisking constantly until a light golden brown.
- Slowly drizzle in milk + cream – use a whisk to evenly incorporate the liquids into the roux to avoid lumps
- Cook sauce over medium heat – once the milk and cream have been added, cook the sauce over medium heat and stir often to avoid burning. The sauce is done when it’s bubbly and can coat the back of a spoon.
- Fold in Parmesan offheat – this will prevent the cheese from burning. Once the sauce is thickened, remove from heat and whisk in Parmesan until melted.
- Broil to brown breadcrumbs – once the gratin is baked you can optionally add a 1-2 minutes broil to crisp up the breadcrumbs a bit more.
Recipe Variations
Try these ideas for a different twist on this cauliflower.
- Add more vegetables – try using half cauliflower and half broccoli. You can also add other vegetables like sweet pepper, mushrooms, carrot, or green beans.
- Use a different cheese – try sharp cheddar, asiago, or gouda in place of the Parmesan.
- Swap out herbs – try fresh thyme or sage in place of the rosemary.
Make Ahead Instructions
Follow these instructions for time-saving make ahead instructions
- Roast garlic and cauliflower – once roasted, these ingredients store well in refrigerator up to 4 days before assembling gratin.
- Assemble gratin – follow steps 1-6 with the exception of topping with breadcrumbs, wrap gratin pan well, and store in refrigerator up to 4 days before baking. Allow to sit at room temperature 30 minutes before topping with breadcrumbs and baking per recipe instructions.
Unsurprisingly, the roasted garlic is absolutely magic in this cauliflower gratin. It lends the most incredible mellow, nutty flavor to the creamy cauliflower and pairs like a dream with all those crispy rosemary breadcrumbs.
Seriously, I dare you to eat any other side dish on the table but this.
Save this recipe using the ‘save to recipe box’ button below. If you make it, please let us know! Leave a comment + star rating below, or take a photo and tag it on Instagram with #wholeandheavenlyoven.
More Thanksgiving side dishes to add to your menu!
Roasted Garlic Cauliflower Au Gratin
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Ingredients
- 1 medium head garlic
- 1 tablespoon olive oil
- Salt and pepper to taste
- 1 large head cauliflower, cut into 1-inch florets
- 1/4 cup unsalted butter
- 1/4 cup all-purpose flour (spooned and leveled)
- 2 cups 2% or skim milk
- 2 tablespoons heavy whipping cream
- 1/2 cup grated Parmesan cheese
- 1/2 cup panko breadcrumbs
- 1 tablespoon minced fresh rosemary
Instructions
- Preheat oven to 400F and lightly grease a large sheet pan. Slice about 1/2-inch off the top of garlic. Arrange garlic in the center of a tin foil rectangle, drizzle with olive oil, and season with salt and pepper. Fold edges of foil over garlic and tightly seal to form a packet.
- Place foil packet on prepared large sheet pan and roast at 400F 35 minutes. Push foil packet to the edge of pan and arrange cauliflower on remainder of sheet pan. Season cauliflower with salt and pepper to taste.
- Roast cauliflower alongside roasted garlic 15-20 minutes until cauliflower is crisp-tender. Allow roasted garlic to cool slightly, then remove from foil and skins and finely mash into a paste. Keep oven on and set aside.
- In a medium saucepan over medium heat, melt butter. Whisk in flour and let cook 2-3 minutes until golden brown. Slowly drizzle in milk and cream, whisking constantly until smooth and incorporated.
- Cook sauce over medium heat, stirring occasionally until sauce is bubbly and thickened. Remove from heat and add cheese and mashed roasted garlic, stirring until cheese is melted.
- Fold roasted cauliflower into sauce and season with salt and pepper to taste. Scrape mixture into a greased 9×13 baking dish and top with panko breadcrumbs and rosemary.
- Bake cauliflower at 400F 20-25 minutes until bubbly. Optionally, broil 2-3 minutes on high to brown breadcrumbs. Serve au gratin warm and enjoy!
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