Prep: zest the lemon, halve tomatoes, mince garlic, and pat the chicken dry. Mix smoked paprika, oregano, garlic powder, 1 tsp salt and ½ tsp pepper; rub onto chicken.
Sear chicken: heat 1 tbsp olive oil in a large skillet over medium-high. Add chicken (skin-side down if using skin-on) and sear 4–6 minutes until golden. Flip and sear 3–5 minutes. Remove to a plate and tent with foil. (Chicken will finish cooking later.)
Roast tomatoes in the same pan: add another ½ tbsp olive oil if needed, toss in halved cherry tomatoes with a pinch of salt. Cook 5–7 minutes until blistered and slightly jammy. Remove and set aside.
Build the orzo base (one-pan method): add remaining olive oil to the skillet, lower heat to medium, sauté sliced onion (if using) 1–2 minutes, then add minced garlic and cook 30 seconds until fragrant. Add the dry orzo and toast, stirring, for 1–2 minutes.
Add liquid: pour in the warm stock (3 cups) and bring to a gentle simmer. Partially cover and cook, stirring occasionally, until orzo is al dente and most liquid is absorbed (about 8–10 minutes). If it dries too fast, add water or extra stock ¼ cup at a time.
Finish creamy base: reduce heat to low. Stir in heavy cream (if using), Parmesan, lemon zest and lemon juice. Adjust thickness with reserved stock or a splash of pasta water — you want a silky coating, not a dry grain. Season to taste with salt and pepper.
Fold in veggies and protein: gently fold in roasted tomatoes and baby spinach (in batches if needed) until wilted. Return chicken to the pan to warm and finish cooking (internal temp 165°F / 74°C) or slice and nestle on top for 2–3 minutes to heat through.
Final touches: scatter chopped parsley, basil, and crumbled feta. Give a gentle toss. Taste and adjust with more lemon, salt, or pepper as desired.
Serve: plate warm, finish with extra Parmesan, a drizzle of good olive oil, cracked black pepper, and lemon wedges.