Asparagus soup with parmesan shortbread

Shortbread
Flour, all-purpose	1 ½ cups
Parmigiano-Reggiano cheese, freshly grated	1 ½ cups (6 ounces)
Thyme, dried	1 teaspoon
Salt, kosher	1 teaspoon
Butter, unsalted, softened	¾ cup
Egg yolks	2
Soup
Butter, unsalted	2 tablespoons
Onions, medium, thinly sliced	1
Asparagus, cut into 1-inch pieces	1 ½ pounds
Chicken broth, low sodium	1 quart
Tarragon leaves	¼ cup + garnish
Parsley, flat-leaf	1 tablespoon
Cream, heavy	¾ cup
Peas	½ cup
Salt
Pepper, freshly ground
Lemon zest	garnish

Shortbread

1. In a standing mixing with the paddle fitted, combine the flour, cheese, thyme, and salt.
2. Add the butter and egg yolks, and beat at medium speed until lightly moistened crumbs form.
3. Gather crumbs, and knead to form a 2-inch-thick log.
4. Wrap in plastic, and refrigerate about 30 minutes to chill.
5. Preheat the oven to 325°F, and line two baking sheets with parchment paper.
6. Slice 1/4 inch thick, and arrange on the baking sheets.
7. Bake for about 20 minutes, until golden around the edges; let cool on sheets.

Soup

1. In a large pot, melt the butter.
2. Add the onion, cover, and cook over moderate heat, stirring occasionally, until softened, about 6 minutes.
3. Add the asparagus, and cook for 1 minute.
4. Add the broth, and simmer until the asparagus is tender, about 10 minutes.
5. Add the tarragon and parsley leaves.
6. Working in batches, puree the soup in a blender.
7. Return the soup to the pot, add the cream and peas, and rewarm.
8. Season with salt and pepper; garnish with lemon zest and tarragon leaves.
9. Serve with Parmesan shortbread.