Place spinach in a medium-large salad bowl. Sprinkle on mushrooms and walnuts.
PREPARE THE DRESSING:
In a small saucepan, heat the oil over medium heat and add the prosciutto and garlic. Stir and cook until the garlic is lightly browned. Stir in the wine, lemon juice and sugar, and continue to simmer for about 5 minutes, stirring every once in a while.
Pour the hot dressing over the salad and toss. Divide the salad between four serving plates and sprinkle each with Parmesan cheese.
Notes
*If you are preparing this recipe as gluten-free, just be sure to use a brand of prosciutto that is know to be GF.
Nutritional information is figured using raw nuts.