Place crab, egg, bread crumbs, mayonnaise, Old Bay spice, lemon juice, onion powder and pepper in a large bowl.
Form mixture into 6 patties.
Heat butter in a skillet over medium heat. Cook the patties until they are browned on each side, about 5 minutes per side.
Serve straight from the stove, or place on hamburger buns for crab cake sandwiches.
To use imitation crab (which is much less expensive than the real thing), pulse it through the food processor just once or twice, or just chop it finely, for a better texture in your crab cakes.
You can form the patties ahead of time and refrigerate for a day or two, or freeze for up to 3 months, prior to cooking. If you freeze them, thaw them in the refrigerator overnight and then follow the above instructions to cook them.
Or, you can cook them ahead of time and then refrigerate or freeze. Thaw frozen patties overnight in the refrigerator prior to reheating. Reheat in the oven at 350 degrees until hot. If they start to get dried out, loosely cover with aluminum foil.
Try with chipotle mayo or tartar sauce for even more flavor!