1

In a 1-cup glass measure, combine porcini mushrooms and 1/2 cup boiling water. Let stand until mushrooms are softened, about 20 minutes. Transfer mushrooms with their liquid to a sieve set over a medium bowl. Reserve liquid. Rinse mushrooms to remove any grit, then pat dry and finely chop. Pour reserved mushroom liquid into a 3- or 4-qt slow cooker.

2

In a large nonstick skillet over medium heat, warm oil. Add onion and cook, stirring, until softened, about 5 minutes. Add carrot and celery and cook, stirring, until slightly softened, about 4 minutes. Add garlic and cook, stirring constantly, until fragrant, about 30 seconds longer.

3

In slow cooker, combine porcini mushrooms, cremini mushrooms, onion mixture, salt, pepper, and broth. Cover and cook 3 hours on High or 6 hours on Low.

4

Meanwhile, wipe skillet clean and set over medium heat. Arrange prosciutto in one layer and cook until crisp, about 5 minutes per side. Transfer to a paper towel–lined plate to drain. When cool, break into 1-inch pieces. Set aside.

5

Ladle soup evenly into 4 bowls. Top each serving with 2 tbsp Parmesan and one-fourth of prosciutto; sprinkle with parsley.

6

Per serving: about 1 cup soup and 2 tbsp cheese