01 - Preheat oven to 425°F. Line a large baking sheet with parchment paper.
02 - Whisk together Dijon mustard, maple syrup, olive oil, garlic, vinegar, salt, and black pepper in a bowl. Add chicken breasts and toss to coat thoroughly. Marinate for at least 15 minutes.
03 - Toss sweet potato cubes on the prepared baking sheet with olive oil, paprika, and salt. Spread in an even layer. Roast for 25-30 minutes, flipping halfway through, until tender and golden.
04 - Heat a grill pan or skillet over medium heat. Remove chicken from marinade and grill or sear for 6-7 minutes per side, until cooked through and juices run clear. Let rest for 5 minutes, then slice.
05 - Whisk together Dijon mustard, maple syrup, olive oil, lemon juice, salt, and pepper in a small bowl until well combined.
06 - Arrange spinach or mixed greens in 4 large bowls. Top each with roasted sweet potatoes, cherry tomatoes, red onion, and sliced chicken.
07 - Drizzle dressing over each bowl. Add optional toppings like feta cheese, fresh parsley, or pumpkin seeds before serving.