Meanwhile, we pre-heat the oven to 300 degrees. We get a medium bowl ready for the coating. We add the flour, the rest of the Old Bay, stir with a fork, and add salt and pepper to taste. We also get ready a dinner plate with paper towels to drain the pan-fried crabs and a cookie sheet with parchment paper to keep the cooked crabs warm in the oven.
When the crabs have soaked for at least 20 minutes, we remove them from the fridge. Instead of using a frying pan, we use a large pot to pan-fry the crabs since they will cause a lot of splattering. We add ¼ inch of oil to the pot and begin heating. When hot, we add half of the butter.
Taking 2 crabs at a time, we lift them out of the buttermilk, add them to the flour, and toss to coat. We try to shake off as much flour as possible and, when the butter has melted and the foam subsided, we carefully add the crabs to the pot with tongs. We cook for 3 minutes on one side, and turn over with clean tongs when they are nicely browned. We cook for another 2 minutes and then drain on the paper-towel lined plate. We put these on the cookie sheet and place in the oven. Off heat, we wipe the pot clean with tongs and paper towels since the oil got a bit dark. We add more oil and the rest of the butter and we repeat the pan-frying with the rest of the crabs. We serve the drained crabs along with the reserved ones in the oven.