Preheat oven to 400 F.
Heat up 1 tbsp olive oil on medium heat. Add the onions, and saute for 4-5 minutes until soft and translucent.
In a medium bowl, toss together potato slices with ½ cup each of the cheddar and Parmesan along with 1 tbsp oil and some salt and pepper.
Add onions to the bottom of a baking dish, and arrange the potatoes in layers.
Pour over veggie broth, and then top with remaining cheese.
Cover with foil and bake for 50 minutes.
Remove foil, and then broil on high for 5 minutes.
Top with chopped chives
