Pre-heat the oven to 350F.
Season chicken breasts with olive oil, salt and thyme.
Place in the pre-heated oven and bake 30 minutes or internal temperature reaches 165°F.
Remove from the oven and allow to cool; rip cooked chicken into roughly 1-½ inch pieces.
Halve the cranberries and smash in a bowl.
In a separate bowl, mix together mayonnaise and Dijon mustard.
Combine cranberries, chicken and mayonnaise mixture until incorporated.
Butter the sliced potato bread.
Add the chicken mixture and a layer of watercress.
Cut off the crusts and slice into rectangles.