Preheat oven to 425°F and line a large sheet pan with parchment paper.
In a small bowl, whisk together Dijon mustard, honey, 1 tablespoon olive oil, minced garlic, thyme, salt, and pepper.
Arrange chicken thighs skin-side up on one side of the sheet pan and brush generously with half of the honey mustard mixture.
Toss potatoes and green beans with remaining olive oil, salt, and pepper, then spread on the other side of the pan.
Roast for 30-35 minutes until chicken reaches 165°F internal temperature and skin is crispy, brushing chicken with remaining glaze halfway through.
Let chicken rest for 5 minutes before serving with the roasted vegetables.