Place the cream over medium heat until steam rises and the cream is hot. Shred the cheddar and place in a blender, add the hot cream and allow to sit for 4-5 minutes. Blend over high speed until smooth.
TO MAKE THE SANDWICH:
Cook the onions over high heat on a flat top or large pan, until caramelized.
Add the beef, and cook for another minute or so.
Cover the beef in 2 oz of the Frita sauce and allow the sauce to reduce on the beef and onions.
Slather the cheese sauce on the Cuban bread, and the beef, onions and potato sticks. Garnish with crispy potatoes.