Put the shrimp on top of the salt in one of the pans, then cover with all of the salt from the second pan. The shrimp should be evenly and completely covered. Roast for 8 minutes. Remove from oven and check one shrimp for doneness — the shrimp should be white and pink in color instead of grey. If not done, return to oven for 1 to 2 minutes. Serve immediately.