Heat oven to 375°F and lightly grease a 1‑quart baking dish.
Beat cream cheese in a bowl until smooth. Stir in mayonnaise and sour cream.
Fold in cheddar, Parmesan, pimentos, and most of the green onions.
Season with Worcestershire, garlic powder, onion powder, smoked paprika, cayenne, black pepper, and salt. Add hot sauce if using.
Spread into the dish and smooth the top. Bake until hot and bubbling at the edges, 18–22 minutes.
Broil 1–2 minutes for extra color if desired. Rest 5 minutes, garnish with remaining onions, and serve warm.