Creamy Miso Pasta with Walnuts and Roasted Cabbage

Name: Creamy Miso Pasta with Walnuts and Roasted Cabbage
Ingredients: 10 oz. whole-grain spaghetti (we used Barilla); 1 small red cabbage (about 2 pounds), cored and thinly sliced lengthwise; 3 1/2 tbsp. olive oil, divided; Kosher salt and pepper; 2 tsp. rice vinegar; 1/2 c. walnuts, chopped; 1 medium onion, thinly sliced; 2 cloves garlic, finely chopped; 1/2 c. low-sodium vegetable broth; 1/2 c. heavy cream; 1/4 c. red miso; 1/4 c. finely grated Parmesan cheese, plus more for serving; 1/2 c. flat-leaf parsley leaves, chopped