Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the smoked Gouda cheese, cream cheese, and sour cream. Mix until well blended and smooth.
Stir in the crumbled bacon, chopped green onions, garlic powder, black pepper, and cayenne pepper if using. Mix until all ingredients are evenly distributed.
Transfer the mixture to a baking dish and spread it out evenly. Top with the shredded cheddar cheese.
Bake in the preheated oven for 25-30 minutes, or until the dip is bubbly and the top is golden brown.
Remove from the oven and let it cool for a few minutes before serving.