Preheat oven to 350 & start boiling water for pasta.
While waiting for water to boil for pasta, melt 1 stick of butter in microwave or on stovetop. While butter is melting, crush up a full sleeve of Ritz crackers. (I do this in quart-size Ziploc Slider bag.) When the butter is fully melted, add in Ritz crackers and toss until butter is absorbed.
Add pasta to boiling water and cook until tender; drain; and set aside.
Melt 1 stick butter in a medium saucepan on medium heat. Whisk in flour; cook, stirring constantly, until well-blended. Gradually stir in milk and bring to a boil. Add VELVEETA, stirring frequently, until melted. Add a splash of cream and a handful of shredded cheese, stirring until blended. Repeat alternating between cream and cheese, stirring, until you have used most of the cheese (save the rest to sprinkle on top).
Put pasta back into pot and pour cheese sauce over; stir until well-mixed. Pour pasta and cheese sauce into a casserole dish or pan, stir in about half of the cracker mixture and salt & pepper. Top with the rest of the cracker mixture & the rest of the cheese.
Bake for 15-20 min @ 350, or until cracker mix is toasted.