Heat 1 teaspoon oil in heavy large skillet over medium heat. Add bell pepper and saute until crisp-tender, about 8 minutes. Transfer pepper to small bowl. Heat same skillet over high heat. Add spinach and saute 2 minutes. Reduce heat to medium and saute until spinach is tender, about 2 minutes longer. Cool in skillet. Transfer spinach to work surface; chop spinach. Set aside. Heat 1 teaspoon oil in same skillet over medium heat. Add garlic and saute until fragrant, about 30 seconds. Add prosciutto and saute 30 seconds. Add chopped spinach. Saute 2 minutes. Season to taste with salt and pepper. Remove from heat. Mix in cream. Preheat broiler. Arrange bread slices on large baking sheet. Broil until lightly toasted. Turn bread slices over. Brush top of bread slices with remaining 2 tablespoons oil. Broil until lightly toasted. Cool. (Components can be made 8 hours ahead. Cover spinach mixture and bell pepper strips separately; refrigerate. Store toasts airtight at room temperature.) Spoon generous 1 tablespoon spinach mixture atop each toast. Arrange bell pepper strips atop toasts. Sprinkle with Parmesan cheese. Broil crostini until cheese bubbles and spinach mixture is hot, about 2 minutes. Transfer crostini to plate and serve.