Prep this Ham Souffle Roll the night before, then bake and serve in the morning for a delicious brunch.
Preheat oven to 375°F. Line a 15x10x1-inch baking pan with foil, extending foil about 1 inch over edges of pan. Grease and lightly flour foil; set pan aside.
In a medium saucepan, melt butter. Stir in flour and pepper. Gradually stir in milk. Cook and stir until mixture is thickened and bubbly. Cool slightly. Place egg yolks in a medium bowl; gradually stir in milk mixture.
In a large bowl, combine egg whites and cream of tartar. Beat with an electric mixer until stiff peaks form (tips stand straight). Fold some of the beaten egg whites into the egg yolk mixture. Fold egg yolk mixture into the remaining beaten egg whites. Spread in the prepared baking pan.
Bake about 20 minutes or until soufflé is puffed and a knife inserted in center comes out clean.
Meanwhile, place a long sheet of heavy foil (about 22x18 inches) on a large baking sheet. Generously grease the foil. Immediately loosen edges of soufflé from baking pan. Invert soufflé onto the foil-lined baking sheet. Carefully peel off foil.
Place ham and cheese slices in single layers on top of soufflé. Starting from a short side, use foil on baking sheet to lift and help roll up soufflé. (Don't roll the foil inside.) Use foil to lift soufflé roll into a 13x9x2-inch baking pan. Fold the foil over soufflé roll to cover; chill for 2 to 24 hours. Prepare Parsley Sauce; cover and chill for up to 24 hours.
Preheat oven to 350°F. Bake soufflé roll, covered with the foil, about 45 minutes or until heated through. Meanwhile, shake sauce; transfer to a medium saucepan. Cook and stir over medium heat until thickened and bubbly. Cook and stir for 2 minutes more.
To serve, uncover soufflé roll. Use the foil to lift soufflé roll from pan. Using two large spatulas, transfer soufflé roll to a warm serving platter (or use foil to roll soufflé onto platter). If desired, spoon a little sauce over soufflé roll. Slice with a serrated knife and serve with the remaining sauce. If desired, garnish with snipped parsley.
In a blender or food processor combine fresh parsley sprigs, shallots and basil. Cover and blend or process until finely chopped. Add whipping cream, cornstarch, Dijon-style mustard, and salt. Cover and blend or process for 10 to 20 seconds or until mixture is slightly thickened. (Be careful not to over blend or you will end up with butter.) Transfer mixture to a screw-top jar.