Heat a large skillet over medium-high heat and add the avocado oil.
Add the ground chicken and season with salt, pepper, and garlic. Break it apart as it cooks using a spatula or meat masher. Cook until browned and fully cooked through, about 8-10 minutes.
Reduce the heat to low and add the cheese slices directly over the cooked ground chicken. Stir until the cheese melts completely and coats the meat.
Taste and adjust seasoning if needed.
Spoon the cheesy chicken mixture into the hoagie rolls and serve.
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Notes
Substitutions: Provolone or mozzarella can replace American cheese. Ground turkey is an easy swap for chicken. Storage: Store filling in the fridge for up to 3 days, or freeze for up to 2 months. Reheat: Reheat gently in a skillet with a splash of water until warmed through.