Preheat your smoker to 350 degrees F, then bring a large stock pot full of heavily salted water to a boil. Once boiling, add the pasta and cook until al dente, about 9 minutes. Strain the pasta and rinse with cold water. Move the pasta to an aluminum foil 9x13 tray and set aside.
Next you will construct your cheese sauce. Place a large sauce pan over medium heat and melt your butter. add the onion and sauté until it is translucent. Now whisk in the flour, making sure to combine it all well, and cook the paste for one minute.
Now, whisk in the heavy cream and chicken broth. Then add the salt, pepper, cayenne, and paprika. Cook this for 3-5 minutes, stirring occasionally until the sauce starts to thicken.
Reduce the heat the low and mix in the Cheddar and Gruyere Cheeses. Mix until the chesses are fully melted into the sauce. Now, pour the cheese sauce over the prepared pasta, then mix until all the pasta is coated in sauce. Level out the macaroni and cheese in the pan.
Sprinkle the blue cheese crumbles over the top of the mac and cheese, then sprinkle crumbled Ritz Crackers over everything. Cover the macaroni and cheese with aluminum foil.
Place in smoker and cook for 20 minutes cover and then an additional 20 minutes uncovered. Serve warm