1 pound asparagus, trimmed
1 sheet frozen puff pastry (about 1/2 pound), thawed
All-purpose flour, for dusting
1 cup grated gruyere cheese
1 tablespoon minced shallot
1 egg beaten
1/8 teaspoon freshly grated nutmeg
Kosher salt and freshly ground pepper
2 teaspoons extra-virgin olive oil
1/2 teaspoon finely grated lemon zest
Remove your puff pastry from the freezer to thaw. Set the Solavore Sport outside to pre-heat.
Wash the trimmed asparagus and put it in your graniteware pot. Cover and place in the oven. Let the asparagus cook for about 20 minutes.
Place the puff pastry on a floured surface and roll into an 8-by10 inch rectangle. Transfer to a parchment-lined baking sheet (a 9x13 baking sheet works well and fits in the Solavore Sport). Prick the puff pastry all over with a fork. Bake until it puffs up, approximately 30 minutes. Let cool slightly on the baking sheet
Meanwhile, mix the gruyere, shallot, egg, nutmeg and a pinch each of salt and pepper in a bowl until combined. Spread the cheese mixture evenly over the puff pastry, leaving a 1-inch border on all sides. Toss the asparagus with the olive oil, 1/4 teaspoon salt, and pepper to taste. Arrange the asparagus on the tart and bake until the edges are nicely browned, 75 to 90 minutes. Sprinkle with the lemon zest. Serve warm or at room temperature.