Melt butter in a heavy saucepan over low heat; add flour, stirring until smooth. Cook 1 minute, stirring constantly. Gradually add 2 cups milk; cook sauce over medium heat until thickened and bubbly, stirring constantly.
Beat egg yolks until thick and lemon colored. Gradually stir one-fourth hot white sauce into yolks; add to remaining white sauce, stirring constantly. Stir in breadcrumbs, ground ham, and pepper.
Beat egg whites (at room temperature) until stiff but not dry. Gently fold into ham mixture. Spoon into a 1 1/2-quart soufflé dish. Bake at 300° for 1 1/2 hours or until lightly browned. Serve immediately.