Thaw frozen corn and pat dry with paper towels. Line a 15x10x1-inch baking pan with foil; use a little of the cooking oil to lightly grease the pan.
Spread corn in prepared pan. Roast, uncovered, in a 450 degree F oven for 10 minutes; stir. Continue to roast about 10 minutes more until golden brown, stirring once or twice. Remove pan from oven and set aside.
In a 4-quart Dutch oven, cook onions and sweet peppers in remaining oil over medium heat for 3 to 4 minutes or until nearly tender. Add the corn, 3 cans of the broth (about 5-1/2 cups), thyme, and ground red pepper. Bring to boiling; reduce heat. Simmer, uncovered, 15 minutes.
In a screw-top jar combine remaining 1 can chicken broth and the flour; cover and shake well. Add to soup; cook and stir until slightly thickened and bubbly. Cook and stir for 1 minute more. Stir whipping cream into soup; heat through.
To serve, ladle soup into 12 soup bowls. Divide crabmeat among bowls. If desired, garnish with fresh thyme sprigs. Makes 12 side-dish servings.
Prepare soup as directed, except after simmering soup for 15 minutes, cool, cover, and refrigerate soup mixture up to 2 days. When ready to serve, reheat mixture, thicken with flour, and add cream. Serve as above.