Preheat the oven to 400°F and place wax paper on baking sheet. In a small bowl, whisk together 1.5 tbsp lemon juice, mustard, garlic, honey, ¼ teaspoon salt, and 2 tablespoons of the olive oil. Set aside.
Place the potatoes and broccoli on the pan. Drizzle with the remaining olive oil and about half of the lemon-mustard mixture. Toss to coat. Season generously with salt, pepper and ½ tbsp lemon pepper seasoning. Spread evenly on the pan.
Cut your chicken breasts into roughly 1.5×1.5 inch cubes. Season each your chicken with lemon pepper seasoning and place on the pan also. Drizzle the remaining lemon/mustard mixture over your cubed chicken.
Bake for 25 minutes, tossing halfway through. Cook until the potatoes are tender and the chicken is cooked through. Drizzle with the remaining lemon juice. Serve immediately.