Stuffed Portobello Mushroom Caps with Roasted Root Vegetable Risotto

Name: Stuffed Portobello Mushroom Caps with Roasted Root Vegetable Risotto
Ingredients: 8 large portobello mushroom caps, stems removed and cleaned; 3 1/2 tablespoons olive oil, divided; 1 pound carrots or parsnips, peeled, quartered lengthwise and cut into 1-inch pieces (cubed beets would also be great here, as would rutabaga or celery root); salt and pepper; 5 cups low-sodium vegetable broth; 1 medium white or yellow onion, diced; 1 medium shallot, minced; 2 cloves garlic, minced; 1 cup arborio rice; 1/2 cup white wine; 1/4 cup nutritional yeast; 1 tablespoon fresh thyme leaves; 2 teaspoons lemon juice; Breadcrumbs (optional)