Season the chicken with oregano, paprika, red pepper flakes, salt, and pepper. Then, heat olive oil in a large oven-safe skillet (like a 12-inch cast iron skillet). When the oil is shimmering, add the chicken. Sear on both sides until golden, about 3-5 minutes per side. Remove the chicken to a plate and set aside.
Decrease the heat to medium, add lemon slices, and cook until the lemons release their juices and begin to brown for about 1 minute. Transfer the lemon to the plate with the chicken.
Add the broccoli, orzo, and scallions to the skillet. Cook, stirring occasionally, until the orzo is lightly toasted and the broccoli is bright green.
Deglaze the skillet with a bit of the chicken broth and continue to cook for another minutes, scraping up the browned bits. Then add the remaining broth and lemon slices to the skillet. Top with the chicken and nestle them into the liquid.
Transfer the skillet to the oven and cook, uncovered for 15-20 minutes, or until the chicken is cooked through and the orzo is soft.