Preparation:
1. In a medium bowl stir together chicken, apple, and egg. Add yogurt and mayonnaise; stir to combine. Season to taste with salt and pepper. Serve immediately or cover and chill up to 4 hours.
2. Spread chicken mixture on half of the bread slices. Top with lettuce leaves and remaining bread slices. Cut away crusts if desired. Cut each sandwich into four triangles or squares.
