Cook boneless chicken 8 - 10 minutes in a frying pan.
Cool about 5 minutes on a cutting board then dice the chicken into bite sized pieces.
Dice the celery into small pieces and cut the grapes in half.
Mix the chicken, celery, red grapes, almonds, mayonnaise, salt, and black pepper until combined.
Chill for 1 hour in the fridge then serve on large buttery croissants.