Rich blue cheese and asparagus offer a perfect pairing, and the mascarpone adds a special creaminess that makes this a special appetizer or first course.
In a skillet over medium heat, melt butter. Add onion and garlic and cook, stirring for 3 minutes or until softened. Add asparagus, salt and pepper and cook, stirring for 5 minutes or until tender crisp and bright green. Remove from heat and stir in mascarpone cheese until melted and creamy. Stir in blue cheese until combined.
Preheat oven to 400°F (200°C).
Place tart shells onto baking sheet. Spoon asparagus mixture into tarts. Bake for 12 to 15 minutes or until pastry is golden and filling is bubbly. Let cool slightly before serving.