Boil salted water, cook macaroni to al dente per package directions
Drain pasta, don't rinse, set aside
Melt butter in medium saucepan over medium heat
Whisk in flour, cook 2-3 minutes whisking constantly until golden
Slowly add warm milk while whisking constantly to prevent lumps
Add heavy cream, whisk to combine
Bring to gentle simmer, cook 3-4 minutes until thickened
Whisk in dry mustard, garlic powder, onion powder, paprika, salt, pepper, cayenne
Reduce heat to low
Add shredded cheddar in three batches, whisking after each until melted
Add Velveeta cubes, stir until completely melted and smooth
Check consistency—add milk if too thick
Add cooked pasta to sauce, stir gently to coat completely
Let rest off heat 2-3 minutes
Serve immediately while hot and creamy