In a large skillet, cook sausage over medium heat 6-8 minutes or until no longer pink, breaking into crumbles; drain. In a small bowl, combine mascarpone cheese and pesto.
Preheat broiler. Place bread on ungreased baking sheets. Brush bread slices on 1 side with oil. Broil 3-4 in. from the heat until golden brown, 30-45 seconds on each side. Spread with mascarpone mixture. Top each with sausage, tomatoes, parsley and Parmesan cheese. Serve warm.