Preheat oven to 400°F (200°C). Cut top off sourdough and scoop out insides, leaving a 1-inch thick bread bowl. Brush inside with olive oil and bake for 10 minutes.
Mix cream cheese, sour cream, mayonnaise, and TABASCO® Sauce until smooth. Stir in grated cheeses, green onions, and bacon.
Reduce oven to 375°F (190°C). Fill bread bowl with cheese mixture, top with Parmesan, and bake for 45 minutes to 1 hour.