Preheat oven to 400 degrees. Line a rimmed baking sheet with foil and set aside.
Place butter in small pan over medium heat and cook for 2-3 minutes or until brown bits form on bottom of pan. Make sure to swirl the pan to prevent burning. Remove from heat and set aside.
Place chopsticks on cutting board. Place potato between chopsticks and make thin slices. (The chopsticks will prevent the knife from going all the way through the potato). Repeat with remaining potatoes.
Place sliced potatoes, red onion and garlic cloves on baking sheet. Pour 3 tablespoons brown butter over top and toss to coat. Season with salt and pepper.
Bake in preheated oven for 30 minutes. Baste potatoes with additional 3 tablespoons brown butter and bake for 25 minutes or until cooked to desired doneness. Toss with remaining 2 tablespoons of brown butter and serve. Garnish with chives if desired.