Step 1Heat the oven to 400 degrees.
Step 2Blanch the asparagus in a large pot of salted boiling water just until the spears turn a bright green, about 1 minute. Strain and remove to an ice bath. Cut the spears on the bias into one-fourth-inch-thick pieces. Set aside.
Step 3In a large skillet, saute the bacon over moderately low heat, stirring often, until it has rendered the fat and is crisp, about 15 minutes. Transfer the bacon bits to paper towels to drain. Add the leeks to the drippings and saute until limp and lightly browned, about 5 minutes. Add the sliced asparagus to the skillet, toss lightly to mix, then transfer the mixture to a large mixing bowl.
Step 4In the bowl of a food processor, combine the quark, cream, Parmesan, nutmeg, salt and pepper for about 20 seconds until smooth. Pulse in the eggs, one at a time. (Alternatively, the quark, cream, Parmesan, nutmeg, salt, pepper and eggs can be whisked in a bowl until creamy.) Pour the quark mixture into the large bowl, add the Emmentaler and reserved bacon, and toss well to mix.
Step 5Set the pie shell on a heavy-duty baking sheet and pour in the quark mixture. Bake, uncovered, for 10 minutes. Reduce the oven temperature to 325 degrees and continue to bake until the tart is lightly browned and set like custard, and a knife inserted toward the center comes out mostly clean, 50 to 60 minutes. Remove the tart from the oven and cool on a rack 45 minutes before slicing. To serve, cut into slim wedges.