Heat 1 tablespoon olive oil in a large deep skillet over medium-high heat. Add sliced chicken sausage in a single layer and cook for 3 to 4 minutes, turning once, until browned on both sides. Remove and set aside.

Add remaining olive oil if the pan looks dry. Reduce to medium heat. Add chopped onion and saute for 2 minutes until softened. Add minced garlic and cook 1 more minute until fragrant.

Add dry orzo and stir to coat in the oil and aromatics. Toast for 1 to 2 minutes, stirring frequently, until lightly golden and nutty smelling.

Pour in chicken broth and bring to a boil. Reduce to medium-low and simmer uncovered for 8 to 10 minutes, stirring occasionally, until orzo is nearly tender and most broth is absorbed. Add a splash more broth if it looks too dry.

Stir in broccoli florets during the last 3 minutes. Cover with a lid and let steam until bright green and just tender-crisp.

Return sausage to the skillet. Add lemon juice and Parmesan if using. Stir to combine and season with salt and black pepper. Serve hot.