01 - Preheat oven to 425°F (220°C) and 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. Spread evenly on the prepared baking sheet.
03 - Roast the potatoes for 15 minutes.
04 - While potatoes roast, combine chicken breasts with 1 tablespoon olive oil, remaining smoked paprika, garlic powder, dried oregano, remaining salt, remaining black pepper, and lemon juice. Marinate for 10 minutes.
05 - Add sliced red bell pepper and thinly sliced red onion to the partially roasted potatoes. Toss gently and return to oven. Roast for an additional 15 minutes, until potatoes are golden.
06 - Heat a grill pan or skillet over medium-high heat. Grill chicken breasts for 5 to 6 minutes per side, or until cooked through and juices run clear. Allow chicken to rest for 5 minutes, then slice.
07 - Place fresh spinach leaves in serving bowls. Top with roasted potatoes, sliced grilled chicken, roasted peppers and onions, and halved cherry tomatoes.
08 - Finish with chopped parsley and serve with lemon wedges if desired.