Nothing says indulgence like noshing on some seriously giant Alaskan King Crab legs.

My favorite way to eat them is simple: steamed and then cracked open and dunked in my lemony butter.

Shells being prepared for a crab bisque. Melissa d'Arabian via AP

But here is the secret I want to tell you about today: After you’ve enjoyed that restaurant-quality meal at home, keep those shells. Because you can get a whole second crab-dish from that one purchase by making crab bisque the next day. (Or, stick shells in a freezer bag and freeze them for a couple of weeks, if you want to space out the crab meals.) Tossing the shells in a hot oven for just a couple of minutes brings out a roasty-crab aroma that will create quick depth of flavor for a speedy homemade stock, even if you don’t have a ton of shells. The stock can then be added to a simple roux, a little sherry and a bit of low-fat evaporated milk for a creamy, satisfying soup.

CRAB BISQUE

Start to finish: 1 hour 15 minutes, including 1 hour inactive cooking time

Servings: About 6 servings, 1 cup each

STOCK:

shells from 2 pounds of Alaskan King crab legs

1 teaspoon olive oil

1 carrot, chopped

2 celery stalks, chopped

1 small yellow onion, roughly chopped

1 teaspoon dried tarragon

2 tablespoons tomato paste

3 cloves garlic, smashed

1/2 cup dry white wine

2 tablespoons lemon juice

8 cups water

1 bay leaf

SOUP:

2 tablespoon butter

2 tablespoons flour

1/2 cup dry sherry

6 cups crab stock

1/2 cup organic 2 percent evaporated milk

1/2 teaspoon salt

1/4 teaspoon black pepper

Crabmeat, for garnish (optional)

MAKE THE STOCK:  Preheat the oven to 400 degrees F. Place the crab shells on a baking sheet and roast them in the hot oven until fragrant, about 5-7 minutes.

Meanwhile, place the olive oil in a large pot over medium heat and cook the carrot, celery onion and tarragon until vegetables begin to soften, about five minutes, stirring frequently. Add the tomato paste, and garlic, stir and cook until fragrant and tomato paste deepens in color, about two more minutes. Pour the wine and lemon juice into the pan and let it bubble for a minute or two. Add the crab shells, 8 cups of water and bay leaf. Bring to a simmer, cover and let simmer on low for about 1 hour.

Strain out the solids using a fine meshed sieve, and set the stock aside. You should have about six cups. (If not, add enough water, clam juice, or chicken stock to make it six cups.)

MAKE THE SOUP:  In a soup pot, melt the butter and add the flour, whisking into a thick paste. Allow to cook and bubble for one minute. Add the sherry and whisk as it bubbles and thickens. Slowly add the crab stock, whisking to incorporate the stock into the thickened roux (flour mixture). Bring the soup to a boil and simmer over low heat for 3-5 minutes, until it thickens a little. Stir in the evaporated milk, garnish with crab meat (optional) and serve.