Step 1

Preheat oven to 225 degrees Fahrenheit.

Step 2

Wrap the shaved roast beef in foil like a "packet" and keep in the oven to heat through.

Step 3

Arrange buns on a baking sheet.

Step 4

Brush tops of buns with beaten egg white (or whole egg, or butter); then sprinkle with poppy seeds and minced onion.

Step 5

Bake for 5-6 minutes.

Step 6

Combine the shredded cheddar cheese (4 ounces), American cheese (4 ounces, shredded or cut into cubes) with half and half (1/4 cup) and 1/4 tsp paprika in a small saucepan on medium-low heat.

Step 7

Cover, and stir occasionally until melted, smooth and combined. Turn off heat, or leave on lowest setting while preparing the rest of the ingredients.

Step 8

In a small saucepan, bring the ketchup (1 cup), apple cider vinegar (1/8 cup), sugar (1/2 tsp), paprika (1/2 tsp), garlic and onion powders (1/4 tsp), salt (1/2 tsp), and water (1/4 cup).

Step 9

Simmer the ingredients in the saucepan on medium high heat for 3-5 minutes.

Step 10

Turn off the heat, stir in the mayonnaise (2 tsp) until combined.

Step 11

Top the bottom bun first with a splat of homemade Arby's sauce, then pile with roast beef, then spoon over cheddar cheese sauce, followed by more Arby's sauce. Top with top onion and poppy seed bun.

Step 12

The prepared sandwiches can be kept warm in the oven at 170 degrees Fahrenheit until ready to eat, for up to one hour.