Preheat oven to 350° (177°C). Lightly spray both sides of baguette slices with cooking spray. Place on a large cookie or baking sheet. Bake 10 minutes. Meanwhile, heat a large non-stick skillet coated with cooking spray over medium high heat. Add mushrooms and 1-1/2 Tbsp. of the Mrs. Dash® Garlic & Herb Seasoning Blend. Cook, stirring often, until mushrooms are tender and browned, about 8 minutes. Combine cheese, mayonnaise and remaining 1/2 Tbsp. Mrs. Dash® Garlic & Herb Seasoning Blend; spread over crostini and arrange on a serving platter. Spoon mushrooms over crostini. Serve warm or at room temperature.