Make elbow pasta in salted water according to the directions on the box to be al dente. Drain and mix in 1/4 cup butter. Set aside.
Grate cheese and reserve one cup of cheddar cheese to sprinkle on the top.
In a hot sauce pan melt 1/4 cup butter. Turn heat to medium and add flour. Stir well. Cook for 1 to 2 minutes stirring or whisking constantly until flour cooks a little bit and looks grainy.
Slowly add millk, stirring or whisking often. Slowly add heavy cream whisking often. Cook over medium heat continuting to stir often until the mixture is pretty thick.
Remove from the heat and stir in salt, pepper and smoked paprika.
Add 1 cup of cheese at a time and stir until melted. Continue adding cheese reserving 1 cup of cheddar to sprinkle on top.
Stir in cooked pasta and pour in a lightly greased 9 x 13 inch baking dish. Sprinkle remaining cheddar cheese evenly over the top then sprinkle panko crumbs on top.
Bake in a 350°F oven for 20 to 30 minutes until cheese is bubbling around the edges and warmed through.
If desired place under broiler for 20 seconds to a minute (do not leave dish unattended) until the bread crumbs brown.