Cheesy Copycat Ruth’s Chris Potatoes Au Gratin

Ingredients:

1/2 minced white onion

2 minced garlic cloves

2 tablespoons butter plus more for greasing the baking dish

1/2 tsp. chicken stock

1 1/4 tsp. heavy cream and more if needed

1 1/2 pounds russet potatoes, peeled and sliced ​​1/8 inch thick

3/4 tsp. grated provolone cheese

1/2 tsp. Grated parmesan cheese

2 bed. grated cheddar cheese

Chopped fresh parsley, for garnish