This recipe takes its inspiration from France’s classic onion tart, pissaladière. I was stunned by my first taste of that classic and the idea that onions could be a main event. In this simple recipe, a mix of onion varieties -- red, white, and green scallions -- are tossed with olive oil, thyme, and salt, then layered on a crust gilded with smoky cheese and finished with a dusting of Parmiggiano – Reggiano and a drizzle of heavy cream. The cooked cream tames the edges of the onion and thickens as it cooks.
The amount of onion in this recipe may seem excessive, but believe me, thinly slice them as directed and it will be a revelation.
Cook to Cook: Flip over a heavy duty sheet pan. Now you have a cookie sheet which is exactly what you need to be able to easily slide the tart off the sheet pan and directly onto the rack of the oven. The crust will be crispy and delicious.
1. Preheat the oven to 450 degrees.
2. In a medium sized bowl, combine the onions with 2 tablespoons olive oil, thyme and salt, toss well and set aside.
3. Flip over an 8 ½ x 11-inch sheet pan (see Cook to Cook) and lightly oil.
4. Lightly flour a large cutting board and rolling pin and begin to roll out the dough until it is roughly ½ inch thick. Pick it up and stretch it with your hands to thin it out and begin to work it into a rectangular shape that will fit on the back of the sheet pan. When it is roughly the same size, lay it onto the oiled sheet pan. Continue to work it into shape with your hands, pushing it to the edges of the pan repeatedly as it will want to keep shrinking back.
5. Lightly oil the edges of the dough with a little olive oil then evenly layer the smoked cheese directly on the crust. Drain and discard any liquid from the onion mixture and layer them on top of the cheese. Sprinkle on the Parmiggiano – Reggiano and then evenly drizzle the cream on top.
6. Bake for 15 minutes or until the tart is cooked enough to slip from the baking sheet directly to the top rack of the oven. Flip the baking sheet over and place under the tart to catch any drips.
7. Continue baking another 10 – 15 minutes until the crust is nicely browned on the bottom.
8. Pull from the oven and allow to rest on a cooling rack for 5 minutes. This is a very important step to ensure that the crust stays crispy.
9. Serve hot or at room temperature.
"Vegetables are perishable, so we don't have any indication of what they looked like 500 years ago," says James Nienhuis, a professor in the Department of Horticulture at the University of Wisconsin.