Asparagus and Cheese Tart

INGREDIENTS

• 1 sheet frozen puff pastry (about 1/2 pound), thawed
• Kosher salt and freshly ground pepper
• All-purpose flour, for dusting
• 1 pound asparagus, trimmed
• 1/8 teaspoon freshly grated nutmeg
• 1/2 teaspoon finely grated lemon zest
• 3 tablespoons whole milk
• 1 cup grated comte or gruyere cheese (about 3 ounces)
• 1 cup grated fontina cheese (about 3 ounces)
• 2 teaspoons extra-virgin olive oil
• 2 large egg yolks
• 1 tablespoon minced shallot