Thaw bread loaf on sheet pan coated with olive oil. Once thawed, use fingers to push the dough out until the dough is flat and pushed out into a sheet. Preheat oven to 400 degrees, then season bread.
Add Old Bay, Parmesan and Parsley to top of bread, sprinkling as evenly as possible. Bake for 18-20 minutes until lightly browned. Cool and cut into squares to use as sandwich.
Place shrimp, celery, mayonnaise and Old Bay seasoning in a medium sized bowl, mix with a spoon until seasoning and mayonnaise are evenly distributed on shrimp.
Cut focaccia square in half horizontally and add lettuce to bottom half, top with shrimp salad and the place top half of focaccia to finish sandwich,
Shrimp salad serves about 5 people.
Focaccia serves about 10 people.