½ lb portobello mushrooms (2 large), stems and gills removed and discarded, caps cut into ½-inch pieces (about 1 ½ cups)
3 tbsp olive oil
4 medium garlic cloves, peeled and sliced thin
1 tbsp tomato paste
2 tsp minced fresh rosemary leaves
1 (14.5-ounce) can whole tomatoes, roughly crushed by hand
Place porcini and broth in small bowl for at least 1 hour, up to overnight, to soften dried mushrooms. Lift mushrooms from broth with fork and finely chop. Strain broth through fine-mesh strainer lined with large coffee filter into medium bowl. Set aside mushrooms and broth.
Heat 12-inch skillet over medium heat with olive oil; cook onions, stirring occasionally, until golden brown and softened, 7 to 10 minutes. Add portobellos, chopped porcini, olive oil, garlic, tomato paste, and rosemary; cook, stirring occasionally, until all liquid has evaporated and tomato paste starts to brown, 5 to 7 minutes.
Add reserved chicken broth, crushed tomatoes, and their juices; increase heat to high and bring to simmer. Reduce heat to medium-low and simmer until thickened, 10 to 20 minutes. Season with salt and pepper to taste.
Serve with zucchini noodles or spaghetti, top with parmesan.
