In a large pot of salted boiling water, cook the elbow macaroni according to package instructions until al dente. Drain and set aside.
In the same pot, melt the butter over medium heat. Once melted, whisk in the flour and cook for about 1-2 minutes until golden and bubbly.
Gradually pour in the milk while whisking continuously to avoid lumps. Cook for another 2-3 minutes until the mixture thickens slightly.
Remove the pot from heat. Stir in the Greek yogurt until smooth, then add the shredded cheddar cheese, garlic powder, onion powder, mustard powder, salt, and pepper. Mix until the cheese is fully melted and everything is well combined.
Add the cooked macaroni to the cheese sauce, stirring gently until all the pasta is coated.
Serve hot, garnished with chopped chives or parsley if desired.
Notes
Garnish with fresh chives or parsley for added flavor.