Caramelized onion and apple slab tart

Onions and apples and cheese, oh my! The combination of gooey, rich and nutty cheese, mellow onions, and sweet apples is not to be missed.

I made this one by rolling out a batch of pie crust into one flat sheet, layering on the onions, apples, cheese, and thyme, and then baking until golden and crisp. The easier option would be to use puff pastry and the results would undoubtedly be buttery, crispy, and delicious. In terms of cheese, I used Cabot sharp white cheddar, which I find to be quite tasty, and some Parmesan. I'm also a big fan of Kerrygold's Dubliner Irish cheddar for its sweet, nutty flavor, and Gruyère would also be nice.

The prep consists of making the dough (or skip this whole step and just use puff pastry – Dufour's is the best you can get, in my opinion); then the slicing of apples and onions and shredding of cheese. I'd recommend using a hand-held mandolin for the apples to speed things up and to get really thin slices. Followed by a long, slow sauté of onions to get everything really soft and sweet.

Then you are ready to eat!

Caramelized Onion & Apple Slab Tart  

A single pate brisee dough or 2 sheets of puff pastry
2 apples, cored and thinly sliced or mandolined – you can leave the skin on or peel them, it's up to you
2 large onions, peeled and thinly sliced
Leaves from 3 sprigs of fresh thyme
1 cup grated cheddar cheese
1 cup grated Parmesan, Romano or Gruyère cheeses
Sea salt and freshly grated black pepper to taste
2 tablespoons butter or olive oil – or a mix of the two
A splash of stock, balsamic vinegar or water to deglaze the pan

1. Preheat the oven to 400 degrees F.

2. Caramelize the onions. Melt the butter (or heat the oil) in a large heavy frying pan then add the onions and cook over medium-low heat for a loooong time, stirring every 5-10 minutes to keep them from burning. Once they're finished cooking, deglaze the pan with a little wine, stock, or balsamic vinegar and salt to taste. Please note that to truly caramelize onions, it can take up to an hour, depending on how big the onions are. If you don't have time for this, just sauté them for a few minutes – they'll still be delicious.

3. Roll out the dough or lay out the puff pastry on a heavy baking sheet. Top with the caramelized onions, the thinly sliced apples and the cheese then sprinkle with salt and pepper and bake for 20-25 minutes (checking it at 15 just to be sure you're not burning them) or until the crust is golden brown and the cheese is bubbly with nice crisp areas.