Cook macaroni according to package instructions. Rinse with warm water and drain completely.

In a large saucepan, melt butter over medium-low heat.

Stir in flour; continue cooking over medium-low heat, stirring constantly, 5-7 minutes or until mixture begins to turn golden.

Slowly add milk. Cook, stirring constantly, over medium-low heat until thickened to the consistency of gravy and bubbly.

Remove from heat; add cheese and stir until melted.

Mix cheese mixture with cooked macaroni; pour into greased 9x13 inch casserole dish.

Combine bread crumbs and melted butter; sprinkle over mac & cheese.

Bake at 375 degrees 20-30 minutes or until bubbly.

Remove from oven; top with crumbled bacon, chives, and sour cream.