Preheat oven to 425 degrees F. Quarter onion and place on a baking sheet with eggplant. Season lightly and drizzle with olive oil. Roast for 45 minutes, until eggplant is blackened and the skin wrinkled. Allow to cool. Cut off and discard the end of eggplant. Place eggplant in a food processor with onion, cream cheese, garlic and chili powder and blend until completely smooth. Season pâté with salt, pepper and lemon or lime juice to taste.