Crab Ravioli with Shallot Cream

Name: Crab Ravioli with Shallot Cream
Ingredients: 1/2 tablespoon unsalted butter; 1/2 tablespoon all-purpose flour, plus more for dusting; 1/4 cup half-and-half or whole milk; 1/2 pound lump crabmeat, picked over; 1 large scallion, white part only, minced; 1 teaspoon minced fresh tarragon; 1/2 teaspoon Dijon mustard; Salt and freshly ground white pepper; 48 wonton wrappers; 2 tablespoons unsalted butter; 1 large shallot, minced; 1 cup heavy cream; 1/2 cup clam broth; 2 teaspoons Dijon mustard; 1 tablespoon minced fresh flat-leaf parsley