Stir together chicken, hot sauce, and butter in a microwave-safe bowl. Microwave at HIGH 45 seconds or until heated.
Spread 3 Tbsp. blue cheese dressing evenly over each pizza crust, leaving a 1-inch border around edges. Top evenly with chicken mixture. Sprinkle with cheese.
Bake directly on oven rack at 450° for 8 to 10 minutes or until crusts are golden and cheese is melted. Drizzle remaining 2 Tbsp. dressing evenly over pizzas; sprinkle with green onions, if desired. Cut each pizza into 3 wedges.
Note: For testing purposes only, we used Mama Mary's Gourmet Pizza Crusts. For a softer crust, bake pizza on a pizza pan or baking sheet.