In a large bowl, mix together the crabmeat, mayonnaise, egg, mustard, lemon juice, cayenne pepper, Old Bay seasoning, bread crumbs, salt, and pepper until well combined.

Shape the mixture into 8 small cakes.

In a large skillet, heat the butter over medium heat until melted.

Place the crab cakes in the skillet and cook for 3 to 4 minutes on each side, or until golden brown.

In a separate bowl, whisk together the mayonnaise, minced garlic, lemon juice, salt, and pepper until well combined.

Serve the crab cakes hot with the lemon aioli on the side.