Heat oven to 400°F Spray 34 mini muffin cups with cooking spray. In 3 quart sacuepan, cook & drain macaroni as directed on pkg. Return to saucepan.
Meanwhile, in a 1-quart saucepan, melt butter over medium-low heat. Stir in flour and salt. Cook & stir until mixture is smooth and bubbly. Gradually add milk, stirring constantly, until mixture boils and thinkens. Stir in 3/4 cup of the cheddar cheese until melted. Stir in Parmesan cheese, blue cheese and bacon, until blended. Pour over macroni, stirring until well mixed.
Spoon mixture into mini muffin cups, filling full. Sprinkle with bread crumbs. Sprinkle evenly with remaining 3/4 cup cheese.
Bake 20-25 min or until golden brown. Let stand 10 minute Sprinkle with chives. Remove from pan. Use a sharp pearing knife to help release macaroni cups from pan.