What it is:
These little squares can be an elegant way to start a meal, or they can be used as a hearty snack for any occasion. Whether you’re having a bunch of jersey-clad football fans over for a day of game-watching, or hosting an elegant dinner party, these tarts will satisfy everyone’s taste buds.
1 17.3-ounce package frozen puff pastry (2 sheets), thawed
1/4 cup (1/2 stick) unsalted butter
12 ounces fresh shiitake mushrooms
1 teaspoon coarse kosher salt, divided
1/2 teaspoon cracked black pepper, divided
1 pound pencil-thin asparagus
1 1/2 teaspoons chopped fresh thyme
1 1/2 teaspoons zested lemon peel
1/2 cup crème fraîche
1/2 cup (packed) coarsely grated Gruyère cheese (~ 2 ounces)
Fresh thyme sprigs (for garnish)
What you do:
1. Roll out each pastry sheet on work surface to 10-inch square.
2. Cut each into 4 squares and using small knife, score 1/2-inch border (do not cut through pastry) around inside edges of each square.
3. Arrange squares on 2 rimmed baking sheets.
4. Cover and chill. (This part can be done up to a day in advance)
5. Stem the mushrooms and slice the caps into strips.
6. Trim the asparagus and cut into 1-inch pieces on the bias (diagonally)
7. Melt butter in heavy large skillet over medium-high heat.
8. Add mushrooms; sprinkle with 1/4 teaspoon coarse salt and 1/4 teaspoon pepper. Sauté until tender and lightly browned, about 4 minutes.
9. Transfer mushrooms to large bowl; cool 15 minutes.
10. Add asparagus, chopped thyme, lemon peel, 3/4 teaspoon coarse salt, and 1/4 teaspoon pepper to mushrooms.
11. Mix in crème fraîche and cheese.
12. Cover and chill. (The filling can also be made up to a day in advance)
13. Position 1 rack in top third and 1 rack in bottom third of oven and preheat to 400°F.
14. Mound filling atop pastry squares, leaving 1/2-inch plain border.
15. Bake tarts 12 minutes.
16. Switch the sheets’ positions in the oven and continue to bake tarts until crusts are puffed and golden and filling is cooked through, about 10 minutes longer.
17. Transfer to plates; garnish with thyme sprigs.