01 - Preheat oven to 425°F. Line a large baking sheet with parchment paper.
02 - In a mixing bowl, toss halved baby potatoes with 1 tablespoon olive oil, 1/2 teaspoon smoked paprika, 1/4 teaspoon salt, and 1/4 teaspoon black pepper. Arrange on prepared baking sheet in a single layer.
03 - Roast potatoes in the oven for 15 minutes.
04 - Meanwhile, combine chicken breasts, 1 tablespoon olive oil, remaining 1 1/2 teaspoons smoked paprika, garlic powder, dried oregano, remaining 1/4 teaspoon salt, remaining 1/4 teaspoon black pepper, and lemon juice in a bowl. Marinate for 10 minutes.
05 - Add sliced red bell pepper and red onion to the potatoes. Toss gently to distribute, then continue roasting for 15 minutes or until potatoes are golden and vegetables are tender.
06 - Heat a grill pan or skillet over medium-high heat. Grill chicken breasts for 5 to 6 minutes on each side until fully cooked and juices run clear. Allow chicken to rest for 5 minutes and slice into strips.
07 - Place fresh spinach leaves in serving bowls. Top with roasted potatoes, grilled chicken slices, roasted red pepper and onion, and cherry tomatoes.
08 - Sprinkle with chopped fresh parsley and serve with lemon wedges if desired.