1. Bring a large pot of salted water to a boil. Add the pasta and cook according to package directions.2. In the last 3 minutes of the pasta’s cooking time, add the small broccoli florets to the pot.3. Cook for the final 3 minutes, then drain the pasta and broccoli together in a colander. Shake well to remove excess water.4. While the pasta cooks, make the cheese sauce. In a large pot or Dutch oven, melt the butter over medium heat.5. Whisk in the flour and cook, whisking constantly, for 1 minute.6. Slowly pour in about 1 cup of the milk, whisking vigorously until a smooth paste forms. Gradually whisk in the remaining milk until no lumps remain.7. Add the garlic powder, onion powder, salt, and pepper. Bring to a simmer, stirring often, and cook for 5-7 minutes, until the sauce has thickened enough to coat the back of a spoon.8. Turn off the heat. Add the shredded cheddar and Gruyère cheese to the pot.9. Stir until the cheeses are completely melted and the sauce is velvety smooth.10. Add the drained pasta and broccoli to the pot with the cheese sauce.11. Stir gently to combine, ensuring every piece of pasta and broccoli is coated. Serve immediately.