Set broiler to 400. Line a baking sheet with parchment or a silpat. Spray lightly with nonstick spray.
Place saltines in a food processor and pulse to a fine crumb. Alternatively, crush with your hands. Set aside.
Crack the egg into a small mixing bowl. Add the half and half, Worcestershire sauce and dijon. Whisk well.
Place the crab meat in a medium mixing bowl (drain first if necessary). Add the crackers and stir gently until the crab meat is coated.
Pour the wet ingredients over the crab mixture. Fold with a spatula until incorporated.
To make the crab cakes, fill a 1/3 cup measuring cup with the crab mixture and turn out onto the baking sheet. This will make 7-8 crab cakes depending on how tightly you pack the crab mixture. Top each crab cake with a pat of butter.
Place under the broiler for 10 minutes until golden. Serve with a lemon wedge.