Turn the heat on the pan used to fry the chicken to medium. Add the butter and once the butter has melted, add the onion. Cook, stirring regularly, for 5 minutes until softened. Next, add the sliced fennel bulb and cherry tomatoes. Cook for 5-7 minutes until softened. Season with salt and pepper.
Add the orzo to the pan and cook, stirring for 2-3 minutes or until the orzo begins to turn golden brown. Add the reserved sliced fennel stems and fronds and cook an additional 2 minutes.
Add the white wine and scrape up any browned bits stuck to the bottom of the pan. Cook for 5 minutes, stirring regularly, until the orzo has completely absorbed the liquid. Note: Adjust the heat as necessary to keep the orzo from sticking.
Add the chicken stock, in half cup increments, stirring until absorbed and incorporated before adding more.
Continue adding the chicken stock until all 3 cups have been absorbed. If you need more liquid, add more as necessary. Taste and season with salt and pepper.