Preheat the oven to 375 degrees Fahrenheit.

Prepare the mashed potato crust by making the Buttery Homestyle Flavored Mashed Potatoes according to the package instructions, substituting boiling milk for water.

Once the milk is fully incorporated, stir in the mayonnaise and grated Parmesan cheese. Season with kosher salt and black pepper to taste. Let the mixture cool for 5 minutes.

After cooling, add the beaten eggs and all-purpose flour to the potato mixture. Stir until well combined; the mixture should be thick and dry in texture.

For the crispy outer potato crust, mix together the Idahoan Buttery Homestyle Flavored Mashed Potatoes, panko bread crumbs, and crushed potato chips. Set this mixture aside.

Season the 5-pound bone-in standing rib roast generously with salt and black pepper. Lightly dust the entire surface with all-purpose flour.

Heat a cast iron skillet or a large heavy sauté pan over medium-high heat. Add the canola oil and heat until it begins to shimmer.

Carefully place the rib roast in the pan with the bone side up or fat side down. Sear the roast until it develops a golden brown color on the surface.

Remove the roast from the pan and transfer it to a sheet tray. Allow it to cool for 10 minutes.

Once cooled, brush whole-grain mustard onto the fat side and the underside of the roast.

Spread the mashed potato and egg mixture evenly over the roast, then coat this layer with the crispy potato crust mixture.

Place the prepared roast in the preheated oven and cook for 1 hour.

After 1 hour, turn off the oven but keep the oven door closed. Leave the roast inside the oven for 3 hours to continue cooking gently.

After the 3-hour resting period, turn the oven back on to 375 degrees Fahrenheit to reheat the roast for approximately 10 minutes.

Remove the roast from the oven and let it rest for 15 minutes before slicing and serving.