Cook pasta and set aside.

Cook onion with all the butter till slightly tender.

Blend in flour, cook over low heat, stirring constantly, until smooth and bubbly, remove from heat.

Stir in milk, heat to boiling, stirring constantly for 1 minute, remove from heat. (might take more milk than recipe calls for, use your judgement)

Stir in velveeta and cream cheese till melted, add bacon bits.

Stir together cheese mix and pasta in a 10x12x3 tin pan.

Place in 250°F smoker and stir every 15 minutes for 45 minutes.

Cover with shredded cheese and smoke till melted (5 minutes or so).