In a small bowl, combine softened butter with 4 tablespoons of grated Parmesan cheese and garlic powder. Mix thoroughly until well incorporated and creamy.

Take two slices of your favorite bread and spread the prepared butter mixture generously on one side of each slice. Layer one slice with cheese, followed by turkey cold cuts, then top with another slice butter-side up.

Preheat a nonstick skillet over low heat and place the sandwich in it. Allow it to toast for 5-6 minutes, flipping carefully when golden brown.

While the sandwich is toasting, whisk together mayonnaise, red grape juice vinegar, remaining Parmesan, garlic powder, Italian seasoning, and cracked pepper in a bowl.

Toss fresh lettuce, red onions, and banana peppers together in a separate bowl while coating them evenly in the dressing.

Open the toasted sandwich and fill it with the vegetable mixture. Optionally add sliced tomatoes, slice in half, and serve immediately.