01 - Cook elbow macaroni according to package directions until al dente. Drain thoroughly and set aside.
02 - Cook chopped bacon in a large skillet over medium heat for 6-8 minutes until crispy. Transfer to paper towels to drain, reserving 1 tablespoon of rendered fat.
03 - Melt butter with reserved bacon fat in a large saucepan over medium heat. Whisk in flour and cook constantly for 1 minute to form a smooth paste.
04 - Gradually whisk milk into the roux until fully incorporated. Simmer for 2-3 minutes, stirring frequently, until sauce thickens slightly.
05 - Stir in cheddar, Parmesan, garlic powder, onion powder, salt, and pepper. Continue whisking until all cheese melts completely and sauce becomes velvety smooth.
06 - Add cooked macaroni and half the crispy bacon to the cheese sauce. Fold gently until every piece of pasta is evenly coated.
07 - Gently fold diced avocado and lemon juice into the mac and cheese, being careful not to mash the avocado.
08 - Plate immediately, garnishing with reserved bacon and fresh chives. Serve while hot for optimal texture and flavor.