Prepare the grits one day ahead; cover and refrigerate. Slice and grill the squares right before the party.
Combine the first 4 ingredients in a medium saucepan; bring to a boil. Gradually add grits, stirring constantly with a whisk. Reduce heat, and simmer 10 minutes or until thick, stirring occasionally. Stir in basil, thyme, and parsley. Pour grits into an 8-inch square baking dish coated with cooking spray. Press plastic wrap onto surface of grits; chill for 2 hours or until firm.
Cut grits into 8 (2 x 4-inch) portions. Grill grit cakes for 6 minutes. Carefully turn grit cakes over, and sprinkle each cake with 1 teaspoon cheese. Grill for 6 minutes or until lightly browned and heated through.