Savory Cheddar Apple Tart

adapted from bluejeanchef.com • Serves 8

2 tablespoons butter
1 large yellow onion, diced medium
1 tablespoon fresh thyme leaves or 2 teaspoons dry
sea salt
1/4 cup white wine
3 large red apples, sliced (Fuji, gala, Honey Crisp, or any good red baking apples)
1 sheet frozen puff pastry, thawed
2 heaping cups sharp cheddar cheese, grated
1 egg, beaten

1. Heat a large heavy skillet over medium heat. Add the butter; add the onion and thyme and season with salt. Sauté the onion until it starts to brown, about 10 minutes. While the onions are cooking, prep the apples; cut in half, cut out cores, and thinly slice.
2. Add the wine to deglaze the pan, scraping the bottom of the pan. Add the apples and stir them gently into the onions. Remove pan from heat and let the mixture cool completely. 
3. Heat oven to 425ºF.
4. Roll the sheet of puff pastry out on lightly floured parchment paper to a rectangle to fit a half sheet pan (about 18 x 13). Transfer the dough to the sheet pan using the parchment to lift it. Brush some egg wash on a 1/2 inch border of the rectangle and fold that half inch of the pastry over to create a double crust. Brush egg wash on the top of the edges.
5. Sprinkle half the cheese on the interior of the pastry rectangle. Spoon the apple mixture evenly over the cheese. Sprinkle with the remaining cheddar cheese. 
6. Bake for 30 minutes, or until crust is nicely browned and crisp. Serve immediately.