Place bacon on a baking sheet lined with aluminum foil. Bake for 15 minutes or until crispy. Cut into small chunks.
Heat 1 tablespoon oil in a large saute pan over medium heat. Add sliced onions and saute until softened, about 5 minutes, stirring frequently. Reduce heat to low and continue to cook until onions are caramelized, about 15 more minutes. If the pan becomes too dry, add a couple tablespoons of water. Remove onions from heat and cool.
Mix together onions with bacon, mayonnaise, sour cream, ¼ cup gruyere, chives, garlic powder, salt, and pepper. Pour dip mixture into a baking dish sprayed with cooking spray. Sprinkle ¼ cup gruyere on top. Bake for 20-25 minutes or until the top is lightly browned. Serve warm with chips, crostini or crudite.
Notes
You can prepare the dip ahead of time and bake it before serving.