Discard the cobs and reserve 3/4 cup of the cooking liquid. Drain the kernels and transfer to a food processor. Pulse, adding enough of the reserved cooking liquid to get the consistency of a slightly chunky polenta. Return to the pan and cook over low heat, stirring often, for 5 minutes. Stir in butter and 1/4 teaspoon each salt and pepper. Remove from heat and cover to keep warm.