Preheat oven to 325 degrees. Spread almonds on a small baking sheet and toast in oven, stirring once or twice, until lightly browned, about 5 minutes. Immediately transfer to a plate to cool. In a food processor, combine toasted almonds, flour, salt, pepper and cayenne. Process until almonds are finely ground, about 30 seconds. Place this almond flour in a large bowl. One at a time, dip half the crabs into the milk, then dredge lightly in the almond flour. In a large skillet, heat 1 1/2 tablespoons each butter and oil over medium-high heat until hot but not smoking. Add coated crabs and cook, turning once, until golden brown, about 3 minutes per side. Drain on paper towels. Repeat with remaining crabs. Serves 4.