Step 1 Remove the corn husks by cutting off both ends of the cobs, then peeling off the husks while trying to keep them whole. Scrape off the silk. Place the husks in a large bowl and cover them with warm water and let stand 15 minutes.
Step 2 Working over a bowl, run the tip of a sharp knife down the center of each row of kernels on each cob, then scrape with the dull side of the knife to remove the kernels.
Step 3In a large skillet, melt the butter over medium heat. Add the corn and its juices, the salt, the pepper and the cream, and simmer until the mixture thickens, about 5 to 8 minutes. Remove from the heat and cool, then stir in the grits, baking powder, chiles and cheese. Chill 15 minutes.
Step 4Drain the corn husks and dry them on paper towels. Make ties for the tamales by tearing a few husks into thin strips.
Step 5Overlap 2 or 3 husks on a work surface and spoon 3 tablespoons of the filling into the center. Fold or roll into a package and tie each end with a strip of corn husk. Repeat with the remaining filling.
Step 6In a steamer or a pot fitted with a steamer rack, make a bed for the tamales with the remaining husks. Add the tamales. Cover and steam over low heat for 1 hour, adding more water as necessary.
Step 7Remove the tamales from the steamer and cool for 10 minutes. Serve them in the husks with salsa and sour cream.