Press whole cloves into the orange in vertical rows; cut orange into wedges with cloves in center of each wedge. In a 3 1/2- or 4-quart slow cooker combine orange wedges, ale, ginger beer, and cinnamon.
Cover and cook on low-heat setting for 5 to 6 hours or on high-heat setting for 2 1/2 to 3 hours. Using a slotted spoon, remove stick cinnamon and orange wedges, gently pressing orange wedges against sides of cooker to release juice.
In a medium bowl beat egg yolks with a wire whisk. Slowly whisk in 1/2 cup of the hot ale mixture. Slowly whisk the beaten egg mixture into the ale mixture in the cooker, whisking until frothy; cook and whisk for 1 minute more.
To serve, add 1 or 2 sugar cubes to each serving. If desired, garnish each serving with grated nutmeg.