I wish we had more sprightly way of referring to the day after Thanksgiving. It’s my favorite Friday, reserved not so much for shopping or anything “black” for that matter. Mine is held sacred for a flannel jammie, full belly, sleep in, something delicious out of the oven, a drive to pick out the perfect Christmas tree and maybe a holiday movie or two (“you’ll shoot your eye out”).
This cauliflower and caramelized onion tart is made for just such a day, so deliciously melty and warm. The kind of thing you can cozy up with in the morning and then again later in the day, next to the fire with a glass of wine.
I’ve made a few different cauliflower tarts over the years but this version with caramelized onions is my favorite, by a long mile. It seems to have been made famous in the March issue of Epicurious, 2007 but Google a bit and you’ll find that it’s been replayed and reimagined by a number of great food writers.
In my translation I’ve omitted the truffle oil altogether because what is sold as truffle oil is not actually made with truffle at all. It’s processed with petroleum and, what is basically formaldehyde, using a process that mimics the flavor of truffle. So, I can’t in good conscience promote you good people using it. It’s not at all necessary but I do appreciate the suggestion of truffle flavor, here. If you’d like to make that happen, try to get your hands on a real truffle or search a reputable market for authentic truffle butter. If using truffle you can layer thin slices into the tart during construction (over the onion). If using truffle butter you can melt one tablespoon and toss the cauliflower in the melted butter after roasting.
I also added a bit of rosemary.
You might be tempted to rush things when it comes to caramelizing the onions but try to take it slow. You want to cook them over medium-low heat for around 30 minutes in order to extract the sweetness that makes this tart so extraordinary. You will need to stay close to give them an occasional stir but this is a great time to do dishes and prep the custard. By the way, I love listening to podcasts while I’m cooking. The One Part Podcast is one of my top three these days along with The One You Feed and Elizabeth Gilbert’s Magic Lessons.
I plan on bringing you my Mom’s pie crust recipe one of these days but until then feel free to use the crust or tart shell of your choice. Pre-made, store-bought is perfectly acceptable. I like using pie weights when blind baking pie crusts (baking the crust without its filling). They prevent air pockets and help the crust to hold its shape. This time around I chose to use three small, 4″ tart pans as opposed to one, standard 9″ pan but the measurements in this recipe will accommodate either. If using the small pans be careful to not overfill the tarts (you can see I came pretty close, here).
This Cauliflower and Caramelized Onion tart is a mustn’t miss and exactly the kind of thing we’ll be pulling out of the oven on Friday morning. “In our Christmas Jammies” (…too soon?).
- 1 head of cauliflower, stem removed and cut into florets
- 4 tablespoons olive oil
- 1 tbsp rosemary, chopped
- 1 pie crust or tart shell of your choosing
- 1 yellow onion, thinly sliced
- 1 tablespoon Dijon mustard
- 2 large eggs
- 1 8 oz container mascarpone cheese
- ½ cup heavy whipping cream
- ¼ teaspoon black pepper
- Pinch of ground nutmeg
- 1 cup grated Gruyère cheese
- ⅓ cup Parmesan cheese
- Preheat oven to 425°F (I like to also preheat the pan that I'll be cooking the cauliflower in - cast iron roasting pan is perfect. A large rimmed baking sheet works as well)
- Toss the cauliflower with 2 tablespoons of olive oil, salt and pepper in large bowl.
- Spread the cauliflower evenly in pan and roast 15 minutes.
- Stir the cauliflower and continue roasting until tender, about 15 minutes longer.
- Remove the cauliflower from the oven and toss with 1 tbsp olive oil and rosemary.
- Allow the cauliflower to cool and then slice, thinly.
- Reduce oven temperature to 350°F.
- Press pie crust onto bottom and up sides of a 9-inch tart pan with removable bottom (or 3, 4" mini tart pans) . Line pie crust with foil and fill with pie weights.
- Bake crust 20 minutes.
- Remove foil and pie weights and bake until crust is golden, about 5 minutes.
- Remove from the oven and allow the crust to cool (leave the oven set at 350°F).
- Heat the remaining olive oil in heavy large skillet over medium-low heat. Add onion and sprinkle with salt and pepper.
- Cook until onion is deep golden brown, stirring occasionally, 30 minutes.
- Allow the onion to cool slightly.
- Brush bottom and sides of the crust/s with mustard.
- Spread the onion evenly in crust and layer the cauliflower over the onion.
- Set the tart on a rimmed baking sheet in order to catch any leaks or drips while cooking.
- Whisk the eggs, marscapone, whipping cream, pepper and nutmeg in a medium bowl.
- Stir in the Gruyère.
- Pour mixture evenly over filling in tart pan and sprinkle with Parmesan.
- Bake until tart is golden and center is set, about 40 minutes (see notes).
- Transfer to rack to cool for 15 minutes before serving.