Winter Vegetable-Chicken Paella

Ingredients

1. 1 large leek, white and tender green parts only, halved lengthwise
2. 1/4 cup extra-virgin olive oil
3. 1 pound butternut squash, peeled and cut into 1-inch dice
4. Kosher salt and freshly ground pepper
5. 12 boneless chicken thighs, with skin
6. 1 large onion, finely chopped
7. 10 ounces chorizo or other spicy cured sausage, cut 1/4 inch thick
8. 1/4 teaspoon saffron threads, crumbled
9. 1/4 teaspoon cayenne pepper
10. 2 cups Spanish Valencia rice
11. 3 1/2 cups hot chicken stock
12. One 14 1/2-ounce can whole tomatoes, drained and chopped
13. 1/2 pound Swiss chard, stems discarded, leaves coarsely chopped

1. Preheat the oven to 425°. Brush the leek with 1 teaspoon of the olive oil and arrange on 1 side of a large baking sheet, cut side down. On the other side, toss the squash with 2 teaspoons of the olive oil. Season the vegetables with salt and pepper and roast for 20 minutes, or until golden and just tender. Cut the leek into 1-inch lengths.
2. Meanwhile, heat 1 tablespoon of the oil in a 14- to 16-inch paella pan or skillet. Season the chicken with salt and pepper; cook over moderate heat until golden, 10 minutes. Transfer to a plate. Add the onion and the remaining 2 tablespoons of oil to the pan; cook over low heat until softened. Add the chorizo, saffron and cayenne; cook over moderately high heat, stirring, for 2 minutes. Add the rice and 1 1/2 teaspoons of salt; cook, stirring, for 2 minutes. Stir in the stock, tomatoes, chard, leek and squash.
3. Nestle the chicken into the rice, skin side up. Simmer the paella over low heat for 5 minutes. Transfer to a 350° oven and bake for 30 minutes, or until the stock is absorbed, the rice is tender and the chicken is cooked through. Remove from the oven and cover with a towel; let stand for 10 minutes. Serve at once.