Preheat your oven to 350°F (175°C).
Cook the elbow macaroni according to package instructions until al dente, then drain.
In a large saucepan, melt butter over medium heat, then whisk in the flour to create a roux.
Gradually whisk in the milk until the mixture is smooth and begins to thicken, about 3-5 minutes.
Stir in the shredded cheddar cheese, garlic powder, salt, and pepper until the cheese melts and is thoroughly combined.
Fold the cooked macaroni and broccoli into the cheese sauce until everything is well coated.
Transfer the mixture to a greased baking dish, topping it with breadcrumbs.
Bake in the preheated oven for 25-30 minutes until the top is golden and bubbly.
Remove from the oven and let cool slightly before serving.
