Cauliflower and Caramelized Onion Tart

I love cauliflower.

This is a recent discovery. I had set myself the task of exploring new vegetables and finding preparations that would be acceptable, and even delicious, to my picky palate. The first time we roasted cauliflower, I fell deeply in love.

Since I am also in love with onions, I felt this tart had the potential to be my soul mate. It is spectacular. Roasted cauliflower, caramelized onions, three kinds of cheese and a flaky crust. A cardiologist's nightmare, perhaps, but worth every bite.

Or is it? As delicious as the tart was (well, is, really - we're taking this one sliver by sliver so it should be around for a while), I didn't long for the finished product the way I longed for the roasted cauliflower itself. When I took the tray of cauliflower out of the oven, I took a little taste. And another and another and another. I find that one is never enough - once I break the seal, I start gobbling it up like a kid digging into some Halloween candy. Except this is good for me. I have always loved picking at food during the cooking process, but in this case it was so bad that I had to have Jeff take over chopping it lest I leave too little for the tart. Then we put the bowl in a high place where I couldn't reach. For once, out of sight was out of mind, and the rest of the cooking went off without a hitch.

So the verdict is . . . absolutely delicious. But the work is not really worth it for an everyday dinner with just the two of us. I will save the tart for special occasions, and leave the roasted cauliflower for everyday.

Cauliflower and Caramelized Onion Tart
Adapted from Smitten Kitchen.

1 small head cauliflower (~1 lb), cut into 1" florets

3 1/2 tbsp olive oil

1 large onion, halved lengthwise and thinly sliced

1 tbsp Dijon mustard  (I think I used a bit more than this)

2 large eggs

1 8 oz container mascarpone cheese

1/2 c whipping cream

1/4 tsp black pepper

pinch ground nutmeg  (I forgot to put this in)

1 c grated Gruyère cheese

1/3 c Parmesan cheese

1 savory tart shell (recipe below)

Roast the cauliflower:

Preheat oven to 425°F. Toss cauliflower with 2 tbsp olive oil in large bowl. Spread on a rimmed baking sheet (I always cover mine with foil when roasting to reduce the mess), sprinkle with salt and pepper, and roast 30 minutes, turning florets halfway through. Cool cauliflower, then thinly slice. Reduce oven temperature to 350°F.

(This is where you would parbake a storebought tart shell. I prefer homemade - the recipe below does not need parbaking.)

Caramelize the onions:

Meanwhile, heat the remaining 1 1/2 tbsp olive oil in a heavy skillet over medium-low heat. Add onion, sprinkle with salt and pepper, and cook until the onion is caramelized, stirring occasionally. This will take 30-40 minutes (so, for maximum efficiency, it should be done while the cauliflower is roasting). Cool slightly.

Prepare the tart:

Spread Dijon mustard over the bottom and sides of the pie crust (I used the back of a spoon, as if spreading pizza sauce). (Since I used a 10" tart pan, rather than the 9" recommended in the original recipe, I used a fair bit more than 1 tbsp. And since I couldn't taste the Dijon in every bite, I might put even more next time. I would keep it to a relatively thin layer, though, to avoid getting the crust too soggy.) Spread the onion over the mustard and the cauliflower over the onion. Set the tart on a rimmed baking sheet to protect against leaks (I missed this step and the tart did leak a little, but only between the layers of the pan. Lucky for me.) Whisk eggs, mascarpone, cream and pepper in a medium bowl (if the mascarpone is cold, like mine, a whisk might get messy. A wooden spoon worked better). Stir in Gruyère. Pour the mixture over the filling in the tart pan, and sprinkle Parmesan over the top. Bake until tart is golden and center is set - about 40 minutes. Transfer to rack and cool 15 minutes before serving.

I found that more than one slice of this per day could be deadly, but it does stay well. I just reheated the slices in the toaster oven at 300°F for 10-15 minutes.

Savory Tart Shell

Also from Smitten Kitchen.

1 1/4 c flour

1 tbsp + 2 tsp cornstarch

1/4 tsp salt

6 tbsp butter, diced

1 egg

In a large bowl, combine the flour, cornstarch and salt. Cut the butter in with a pastry blender until the butter is well-blended(generally, no larger than pea-sized chunks). Add egg and mix with a fork until dough comes together. If this does not happen easily(it didn't for me), knead it a bit in the bowl or on the counter, depending on how well it has blended(I still had about a cup's worth of powder in the bowl, so I kneaded it there until it all came together, then did some more kneading on the counter).

On a lightly floured surface, roll the dough into a 12" circle. (Yeah, right. Mine was a horrible, torn, free-form shape. I found this dough difficult to roll out nicely. However, it was easy to take ripped pieces and use them to patch holes later. This worked fine for me.) Place the dough in a 9" pie or tart pan and press to remove any air bubbles. (Ha! Easier said than done. I started to lift the dough and it immediately ripped. I ended up sliding the tart pan bottom under the dough, lifting it on that and carefully putting it back in the pan. This worked pretty well, and it did fit my 10" pan well enough. I then fixed any extra rips or thin places with the excess dough. It looked like a wreck, but once the filling was in, you'd never notice.) Refrigerate crust for 30 minutes, then proceed with filling of your choice. It does not need to be parbaked.