Preheat oven to 450 degrees. Season chicken thighs with sea salt and black pepper and set aside.
Add olive oil to a large, oven-safe skillet over medium heat and allow to get hot for a couple of minutes. Add chicken to skillet and allow to sear for two to three minutes.
Meanwhile, season baby potatoes with garlic powder, sea salt, and black pepper then add melted butter and stir or toss until evenly coated.
Spread potatoes out on a large sheet pan and place in oven to roast for 10 minutes.
Flip chicken thighs over and cook for about five minutes more.
Add brussels sprouts, honey, olive oil, sea salt, black pepper, and crushed red pepper to a large bowl and stir until evenly coated.
Add brussels sprouts to sheet pan with baby potatoes and roast for fifteen minutes then remove from oven.
Spread honey mustard sauce over top of chicken thighs then place entire pan in oven to roast for about 20 minutes. Internal temperature of thighs should reach 165 degrees.