PREHEAT OVEN TO 400 DEGREES F (200 DEGREES C).
CUT 5 SQUARES OF ALUMINUM FOIL 1 1/2 TIMES THE SIZE OF THE EARS OF CORN; PLACE EACH EAR OF CORN IN THE CENTER OF A PIECE OF FOIL.
STIR MAYONNAISE, PARMESAN CHEESE, CHILI POWDER, GROUND BLACK PEPPER, AND FRESH PARSLEY TOGETHER IN A BOWL UNTIL IT FORMS A THICK PASTE; RUB ABOUT 2 TABLESPOONS OF THE PASTE OVER EACH EAR OF CORN. WRAP THE ALUMINUM FOIL AROUND THE CORN AND SEAL. ARRANGE CORN ON A BAKING SHEET.
BAKE IN PREHEATED OVEN FOR 10 MINUTES, TURN, AND CONTINUE BAKING ANOTHER 10 MINUTES.