Combine milk and butter in a medium saucepan over medium heat. Bring to a boil; add flour all at once, stirring constantly, until mixture forms a dough ball and leaves the sides of the pan. Remove from heat. Add eggs, one at a time, stirring constantly and vigorously until mixture is smooth. Add cheese, bacon or ham, green onion, garlic powder, salt, and pepper.
Line a baking sheet with foil; grease. Or, use a nonstick silicone baking mat to line the baking sheet. Drop dough by teaspoonfuls onto the greased foil. Bake at 350° for 25 minutes, or until puffed and nicely browned. Serve warm. Makes about 36 Cheddar Bacon Cheese Puffs.