Preheat oven to 350 degrees F (175 degrees C). Line a baking sheet with aluminum foil.
Mix cream cheese, cheddar cheese, onion, bacon, Smokin' Ts and bread crumbs together in a bowl. Spoon cream cheese mixture into each mushroom. Arrange stuffed mushrooms on the prepared baking sheet.
Bake in the preheated oven until mushrooms are tender and cheese is melted, 30 to 40 minutes.