Combine 2/3 cup evaporated milk with the next 5 ingredients. Add beef; mix lightly. Refrigerate until chilled.
With wet hands, shape meat mixture into 1-in. balls. In a large skillet, heat butter over medium heat. Brown meatballs in batches. Dissolve bouillon in boiling water. Pour over meatballs; bring to a boil. Cover; simmer 15 minutes.
Meanwhile, stir together cold water and flour. Remove meatballs from skillet; skim fat, reserving juices. Add flour mixture and remaining 1 cup evaporated milk to pan juices; cook, uncovered, over low heat, stirring until sauce thickens.