In a large skillet over medium heat, melt the butter.
Add the sliced onions and a pinch of salt. Cook, adding water as necessary, stirring occasionally, for 30-45 minutes, until the onions are golden brown and caramelized.
Add mayonnaise, shredded Kerrygold cheddar cheese, truffle dip, garlic, garlic powder, onion powder, hot sauce, and Worcestershire sauce. Mix until smooth.
Sprinkle crispy onions over the top before serving.
Transfer the mixture to an oven-safe dish. Bake at 375°F (190°C) for 15–20 minutes, or until bubbly and golden.
Serve warm with crackers, chips, or fresh veggies.