In a greased 4-quart slow cooker, stir together cream cheese, chicken, 3/4 cup BBQ sauce, half the bacon, 1 cup cheddar cheese, mozzarella cheese, and garlic powder.
Cover and cook on low for 1 1/2 to 2 hours, stirring halfway through.
Stir until cream cheese is completely mixed in. Drizzle with remaining BBQ sauce. Sprinkle remaining cheddar cheese, bacon, and green onions on top.
Turn to warm and place lid back on for 5 minutes to melt the cheese.