01 - Prepare elbow macaroni according to package directions until al dente. Drain thoroughly and set aside.
02 - Cook chopped bacon in large skillet over medium heat until crispy, approximately 6–8 minutes. Remove with slotted spoon and drain on paper towels. Reserve 1 tablespoon bacon fat.
03 - Melt butter with reserved bacon fat in large saucepan over medium heat. Whisk in flour and cook constantly for 1 minute to form roux.
04 - Gradually whisk milk into roux until smooth. Bring to simmer and cook 2–3 minutes until slightly thickened.
05 - Stir in sharp cheddar, Parmesan, garlic powder, onion powder, salt, and pepper. Continue stirring until cheese is completely melted and sauce is velvety smooth.
06 - Add cooked macaroni and half the crispy bacon to cheese sauce. Stir thoroughly to ensure even coating.
07 - Gently fold diced avocado and lemon juice into pasta mixture, taking care not to mash avocado.
08 - Plate immediately and garnish with reserved bacon and fresh chives.