Toast pecans on baking sheet in 350 F oven for about 5 minutes or until fragrant; set aside. In large heavy skillet, melt butter over medium heat. Add onion and garlic, cook, stirring occasionally, until softened, about 4 minutes. Add mushrooms; cook for 6 minutes over medium high heat, stirring often. Add vermouth, salt and pepper to taste; cook for 2 minutes longer or until most of the moisture has evaporated. Remove from heat, stir in cheese and set aside to cool.
Makesabout 1 1/2 cups.