Combine all spread ingredients except poppy seed in medium bowl. Beat at medium speed until creamy. Reserve 2 tablespoons cheese mixture in small bowl. Cover; refrigerate.
Divide remaining cheese mixture in half (about 2 cups each). Spread one-half into 6-inch circle in middle of serving plate to form brim of hat. Shape remaining half of cheese mixture into 4-inch ball. Wrap each in plastic food wrap; refrigerate 1 hour.
To assemble hat, center cheese ball in middle of hat brim. Shape ball into a cone to form top of witch’s hat. Sprinkle or press poppy seed over entire hat to cover.
Using reserved cheese mixture, attach carrot slices to form hatband. Carefully cover with plastic food wrap; refrigerate at least 2 hours.
Remove from refrigerator about 30 minutes before serving. Serve with assorted crackers and vegetables.
Sliced olives, zucchini or small round crackers may also be used to form hatband.
This fun hat can be made 1 day ahead. Wrap in plastic food wrap; refrigerate. Attach hatband just before serving.