Preheat oven to 400°F (200°C). Bake frozen patties for 20 minutes until crispy. Cool slightly and slice each in half lengthwise.
Spread garlic butter on one side of each bread slice. Mix marinara, basil, and garlic salt in a bowl; microwave for 30–60 seconds and stir.
In a skillet (off heat), layer: Bread (butter-side down), 2 provolone slices, 1 tbsp sauce, 2 chicken halves, 2 more tbsp sauce, 1 provolone slice, top bread slice (butter-side up)
Cook on medium heat for 2–3 minutes per side until golden and cheese melts. Press gently and adjust heat if needed.
Repeat for second sandwich. Warm leftover sauce, add Parmesan, and serve for dipping.