Place the chicken breast in the freezer for 30 to 45 minutes to firm up. Preheat your oven to 400°F. Spread butter inside the hoagie rolls and sprinkle with garlic powder. Arrange the rolls in a single layer on a baking sheet and set aside. Remove the chicken from the freezer and slice it as thinly as possible, then chop into smaller pieces about ¼ to ½ inch. Toss the chicken with garlic powder and salt, then set aside. Heat a large skillet over medium-high heat and melt two tablespoons of butter. Add the sliced onions and jalapeños, sautéing for 7 to 8 minutes until the onions are softened and slightly translucent. Transfer the mixture to a bowl, cover, and set aside. Bake the hoagie rolls for about five minutes. Meanwhile, return the skillet to high heat and add the chicken, cooking for 5 minutes and tossing occasionally until browned and cooked through. Lower the heat to medium, add the remaining tablespoon of butter to the skillet, and stir until melted. Pour in the Frank’s RedHot sauce and mix until the chicken is evenly coated. Place the provolone cheese slices over the chicken and cook until the cheese melts. Use a spatula to transfer the cheesy buffalo chicken to the toasted hoagie rolls, top with the onion and jalapeño mixture, and serve warm.