Pound almonds to make a paste; set aside. Combine flour and 1/4 cup water to form a smooth paste; set aside.
Combine hen, mace, and remaining water in a large stockpot; bring to a boil. Reduce heat; cover and simmer 1 hour or until hen is tender. Remove hen from broth and cool, reserving broth. Bone breasts and wings, and cut meat into bite-size pieces. Reserve remaining chicken for use in other recipes. Combine chicken pieces, almond paste, and 2 cups whipping cream in container of an electric blender; process until smooth. Set aside.
Combine 1 quart reserved broth, remaining whipping cream, breadcrumbs, and pureed chicken mixture in a large Dutch oven. Bring to a boil. Stir in reserved flour mixture, salt, pepper, and hot milk. Heat thoroughly (do not boil). Serve immediately in individual soup bowls. Sprinkle each serving with paprika, if desired.