1. Bring stock to a simmer in a saucepan (do not boil). Keep warm over low heat.
2. Heat a large skillet over medium heat. Add 1 tablespoon oil to pan; swirl to coat. Add pasta; cook 5 minutes or until toasted, stirring frequently. Remove pasta from pan.
3. Add the remaining 1 tablespoon oil, onion, and sausage to pan; cook 4 minutes or until browned, stirring to crumble. Remove sausage mixture from pan. Reduce heat to medium-low. Return pasta to pan. Add stock, 1 cup at a time, stirring constantly until each portion of stock is nearly absorbed before adding the next (about 35 minutes total), stirring frequently. Stir in sausage mixture, juice, chiles, salt, and cheese. Garnish with oregano, if desired.
Skillet-Toasted Penne with Bacon and Spinach: Follow steps 1 and 2. Substitute 4 chopped center-cut bacon slices for the sausage, and 1/2 cup sliced shallots and 8 sliced garlic cloves for the onion. Substitute 1 tablespoon fresh lemon juice and 1/2 teaspoon grated lemon rind for the 2 tablespoons lemon juice. Substitute 6 ounces baby spinach for the chiles. Serves 4 (serving size: 1 cup) Calories 394; Fat 11.8g (sat 3.1g); Sodium 601mg