
Place butter and sugar in bowl. Attach bowl and flat beater. Turn to Speed 6 and beat 1 minute. Stop and scrape bowl. Add egg, orange peel, orange juice, and milk. Turn to Speed 4 and beat 30 seconds.
Combine flour, baking powder, soda, and salt and add to bowl. Turn to Speed 2 and mix 15 seconds or just until moistened. Do not overbeat.
Fill greased muffin tins two-thirds full. Bake at 400°F for 20 to 25 minutes. Serve warm.