Asparagus and Mushroom Tarts

Recipe by Betty Rosbottom
Serves 8 with side salad for lunch

 1  package frozen puff pastry -- 17.13 ounces
   1/4 cup  unsalted butter
 12 oz  mushrooms -- stemmed, caps cut into 1/4-inch-wide strips
 1 tsp  kosher salt -- divided
    1/2 tsp  black pepper -- divided
 1 lb  asparagus spears -- slender - trimmed, cut on diagonal into 1-inch pieces
 1 1/2 teaspoons  fresh thyme -- chopped
 1 1/2 tsp  lemon zest
    1/2 cup  crème fraîche
    1/2 cup  Gruyère cheese -- (packed) coarsely grated
           Fresh thyme sprigs (for garnish)

Roll out each pastry sheet on work surface to 10-inch square. Cut each
into 4 squares. Using small knife, score 1/2-inch border (do not cut
through pastry) around inside edges of each square. Arrange squares on 2
rimmed baking sheets. **DO AHEAD Can be made 1 day ahead. Cover and
chill.**

Melt butter in heavy large skillet over medium-high heat. Add mushrooms;
sprinkle with 1/4 teaspoon coarse salt and 1/4 teaspoon pepper. Sauté
until tender and lightly browned, about 4 minutes. Transfer mushrooms to
large bowl; cool 15 minutes. Add asparagus, chopped thyme, lemon peel, 3/4
teaspoon coarse salt, and 1/4 teaspoon pepper to mushrooms. Mix in crème
fraîche and cheese. **DO AHEAD Filling can be made 1 day ahead. Cover;
chill.**

Preheat oven to 400°F. Mound filling atop pastry squares, leaving 1/2-inch
plain border.

Bake tarts 12 minutes. Reverse sheets. Continue to bake tarts until crusts
are puffed and golden and filling is cooked through, about 10 minutes
longer. Transfer to plates; garnish with thyme sprigs.

Source: Epicurious.com