Preheat oven to 350°F (175°C).

Melt butter in a skillet over medium-high heat.

Add thinly sliced onion to the skillet and stir.

Cook onion, stirring occasionally, until golden brown and soft (about 15-20 minutes).

Remove from skillet and let cool slightly.

In a large bowl, combine shredded Gouda, softened cream cheese, and mayonnaise.

Mix until smooth and well combined.

Stir in cayenne pepper, minced chives, parsley, and garlic.

Gently fold in the caramelized onion and flaked smoked salmon.

Spoon the mixture into an oven-safe dish.

Bake for 25-30 minutes, or until golden and bubbling on top.

Let cool slightly before serving.

Serve warm with crackers, chips, or chunks of bread.