1

Preheat the oven to 400°F. On a floured surface, roll the puff pastry out to a 16-by-10-inch rectangle. Trim uneven edges. Place the pastry on a baking sheet. With a sharp knife, lightly score the dough to form a l-inch border. Using a fork, prick the dough inside the border every 1/2 inch. Bake until golden, rotating the pan once, about 15 minutes.

2

Meanwhile, in a small saucepan with a tight-fitting lid, toss the onion, with 1 tablespoon of the oil. Season with salt. Cover and cook over medium heat until the onion begins to brown, about 5 minutes. Stir. Continue cooking with the cover on for 15 minutes, stirring every 5 minutes. Set aside.

3

In a large saucepan with a tight-fitting lid, heat the remaining tablespoon of oil. Add the mushrooms; cover and cook until tender and all liquid has evaporated, about 10 minutes. Fold in the spinach; season with salt and pepper. Cover and cook until wilted, about 5 minutes more. Drain any liquid.

4

Top the dough with the mushroom-spinach mixture. Scatter the onions and goat cheese on top. Bake until the cheese is lightly browned, about 15 minutes.