In a large pot with a basket, boil the crabs in boiling water, making sure the water covers the crabs. Add the Old Bay seasoning and salt. Cook the crabs until they are red, approximately 10 minutes, and then let crabs cool to the touch. Crack crabs and remove the lungs, leaving the roe in and claws attached. Crack the crab in 2 sections down the middle. In a deep skillet, melt the butter and add the garlic and parsley. Place the crabs in the butter mixture and then on a platter. Pour remaining butter from skillet onto the crabs before serving.