Here is the basic recipe
4 pounds small red potatoes
5 quarts water
1 (3-ounce) bag of crab boil seasoning
4 tablespoons Old Bay seasoning
2 pounds kielbasa or hot smoked link sausage, cut into 1½-inch pieces
6 ears of corn, halved
4 pounds large fresh shrimp, peeled and deveined optional
Add potatoes to large pot, then add 5 quarts water and seasonings. Cover pot and heat to a rolling boil; cook 5 minutes. Add sausage and corn, and return to a boil. Cook 10 minutes or until potatoes are tender.
Add shrimp to stockpot; cook 3 to 4 minutes or until shrimp turn pink. Drain. Serve with cocktail sauce.
However I have been cooking frogmore for almost a decade now and have made several tweaks to improve the finished product.
I do not use the crab boil seasoning bag. Instead I increase the Old Bay to 1/2 of a cup and add about 2 tablespoons of tabasco sauce and approx. 1 tablespoon of cayenne pepper. I also add two sticks of butter to the pot.
I split the sausage into 2 kinds. I use half kielbasa and half italian sausage. The italian sausage & butter makes the food richer. The extra spices gives it a slight kick but not that much. I put the italian sausage in the same time as the potatoes because they take a little longer to cook.
I never have used peeled shrimp. If the pot is at a raging boil when the shrimp are added, they cook really fast with the peel on (they may need a quick stir to get all of them in the water). They are real easy to overcook with the peel off.
Although the cut ears of corn from the supermarket frozen section will do, nothing compares to fresh corn. I have had my best results when using white corn instead of yellow.
I also add 5 minutes of cooking time to all stages (except the shrimp of course).