Spread 2 tbsp of softened butter evenly on one side of each of the 4 slices of bread.
Lay two slices of bread butter-side down. Spread 4 tbsp of marinara sauce evenly across the unbuttered sides.
Evenly distribute the 1 cup of mozzarella cheese and 1/2 cup of cheddar cheese over the marinara sauce.
Layer the 2 oz of beef pepperoni on top of the cheese. Sprinkle with 1 tsp dried herbs, 1/4 tsp black pepper, 1/4 tsp chili flakes, and a pinch of salt.
Place the remaining two slices of bread on top, butter-side facing out.
Preheat a non-stick skillet over medium-low heat. Place the assembled sandwiches in the skillet.
Cook for 4 to 5 minutes until the bottom is golden brown and crispy.
Carefully flip the sandwiches and cook for an additional 4 to 5 minutes, or until the cheese is completely melted and the bread is golden.
Remove from the skillet, let rest for 1 minute, slice, and serve.