Heat a griddle or nonstick skillet with cooking spray and set over medium-high heat to preheat.
In a medium bowl, with a spoon, combine shrimp, mayonnaise, egg, bread crumbs, chives, salt, and black pepper. Mix well and shape mixture into 4 cakes, each about 1-inch thick.
Place cakes on hot griddle and cook 3 minutes per side, flipping with a spatula, until cooked through. Remove from griddle.
While cakes are cooking, in a small bowl, with a spoon, combine mayonnaise and grain mustard. Mix well. Serve shrimp cakes with remoulade spooned over top.