Combine the crabmeat, shrimp, Devonshire cream, saltine crumbs, chives, lemon juice, hot peppers, and cayenne together in a large bowl, and mix thoroughly. Cover and refrigerate 20 minutes.
Remove the crab and shrimp mixture from the refrigerator and form the mixture into 8 equal size patties, about 3 inches round 1/2- to 3/4-inch thick. Press the cakes together firmly so they don’t break apart during cooking. Pour about 1/2 cup flour on a plate and dredge the cakes in the flour to coat all sides.
To cook the cakes, place 2 large nonstick skillets over high heat, add 1/4 cup oil to each skillet, and heat for 2 minutes. Place 4 cakes in each skillet and cook until golden brown on one side, about 1 1/2 minutes. Turn carefully so the cakes don’t break, reduce the heat to medium, and cook 1 minute on the second side. Remove the cakes from the oil and place on paper towels to drain.
Scatter the green on each of 4 plates, dividing them evenly. Place 2 crab cakes on each plate and spoon a dollop of the Spicy Chipotle Mayonnaise alongside. Serve with additional mayonnaise on the side.
