Preheat your oven to 350°F so it’s ready when the pasta and sauce come together.
Bring a large pot of salted water to a boil and cook the elbow macaroni until just al dente. Drain well and keep for later.
In a separate large pot, melt the butter over medium heat.
Add the minced garlic and sauté for about 30 seconds, just until fragrant.
Pour in the evaporated milk, heavy cream, and regular milk, stirring to blend them into a smooth base.
Season the mixture with onion powder, garlic powder, and salt and pepper to taste. Let it gently simmer for about 5 minutes to thicken slightly.
Add the cheddar and Gruyere cheeses, stirring until they fully melt and the sauce becomes creamy.
Fold in the cooked macaroni and about two-thirds of the crumbled bacon, making sure everything is evenly coated.
Transfer the mixture to a 9×13 baking dish, spreading it out into an even layer.
Bake for 25 minutes. If you want a browned top, broil for a few more minutes.
Remove from the oven and garnish with chopped chives and the remaining bacon.
Let it cool slightly, then serve.