Preheat oven to 400 degrees. Spray a baking dish with oil.
Cook pasta in a large pot according to package directions, adding broccoli in the last three minutes.
Transfer to a colander to drain.
Meanwhile, heat oil in a large skillet. Add chicken and cook, stirring occasionally, for about 8 minutes, until cooked through. Add in marinara and ricotta cheese and cook until heated through about 4 minutes.
Stir in pasta and broccoli and toss to combine. Transfer to prepared dish and top with mozzarella cheese. Cook for 10 minutes, until the cheese is melted and bubbly.