Drizzle ½ tablespoon oil in a large pot over medium-high heat and cook the chicken sausage until browned. About 5 minutes. Remove from pan into a bowl and set aside.
Add the remaining oil to the pot and reduce heat to medium. Add the onion and sauté until softened, 2 to 3 minutes.
Add the garlic and continue to sauté until lightly browned, 1 to 2 minutes.
Add the sun dried tomatoes and orzo and stir for 30 seconds to coat the pasta.
Stir in the broth then bring the pot up to a gentle simmer. Stir every few minutes until the pasta is tender and most of the liquid has been absorbed, 6 to 8 minutes. If all the liquid is gone before the pasta is fully cooked, stir in a little more broth or water and continue cooking.
Turn off the heat then add the salt, pepper, parmesan, spinach, browned sausages, and lemon juice (if using). Stir until the spinach in wilted.
Taste the orzo and add more seasoning as needed.
Divide evenly between 6 bowls and top with additional Parmesan and fresh basil, if desired.
