Preheat your oven. Preheat your oven to 350°F
Prepare the shrimp and crab. In a food processor, chop the shrimp until finely ground. Stop before it fully becomes a paste. Remove and set aside. Then pulverize the imitation crab until finely minced. Set aside.
Mix together. In a large mixing bowl, add the chopped shrimp, minced imitation crab, finely chopped green onion, diced yellow onion, minced garlic, diced celery, mayonnaise, shredded cheese, salt and pepper. Mix until thoroughly combined.
Assemble. Slice the french bread diagonally into ¼-1/2 inch thick slices. Add about 1 tablespoon of the shrimp mixture on top of each slice and spread the mixture evenly to the edges.
Bake. Place a single layer of the toast on a baking tray about 1 inch apart from each other and bake for about 20-25 minutes or until the shrimp is cooked through and the top is lightly golden brown. Cool the baked shrimp toast on a wire rack for 5 minutes before serving.