Add vegan butter to your saucepan on medium heat. Once sizzling, add onions and stir until well coated. Season with a pinch of kosher salt.
Lower the heat to low and stir every few minutes for 20 minutes. Cook for another 10 minutes or until dark brown, stirring often.
Mix all ingredients together and place in the refrigerator until ready to serve.
Line a baking sheet with aluminum foil or parchment paper and place frozen fries on the sheet. Bake according to your bag instructions.
Place sliced cheese over fries and put back in the oven until melted (you can also use your broiler if you have one for this).
Top with sauce and caramelized onions and enjoy!