Preheat oven 350°F, fill muffin pan with baking cups.
In mixer bowl, cream butter and sugar. Add eggs, milk, chocolate, vanilla, and orange oil, mixing after each addition. Add flour, baking powder and salt; mix just until blended. Fill each baking liner 2/3 full.
Bake 20-25 minutes or until toothpick inserted in middle comes out clean. Cool in pan on cooling rack 8 minutes. Remove cupcakes from pan. Cool completely before icing.