1. Toss chicken in a large bowl with next 4 ingredients and 1 teaspoon each marjoram and rosemary.
2. Heat 2 tablespoons olive oil in a large sauté pan over medium-high heat. Add chicken, reduce heat to medium, and cook 6 to 7 minutes per side or until a thermometer inserted into the thickest portion registers 165°. Remove chicken from pan, cover loosely with foil, and set aside. Add tomato and any remaining marinating liquid to pan, and cook, stirring constantly, 2 minutes or until tomato skins just begin to shrivel. Remove tomato from pan, cover loosely with foil, and set aside.
3. Bring broth to a boil in a 3-quart saucepan over medium-high heat. Turn off heat, cover, and keep warm.
4. Heat remaining olive oil and butter in the same sauté pan over medium heat until butter melts. Add onion, and sauté, stirring frequently, 2 minutes or until tender and translucent. (Do not scrape bottom of pan.) Add garlic, and sauté, stirring constantly, 1 minute more.
5. Add rice, and cook, stirring constantly, 2 minutes or until grains are well coated and the outsides turn translucent. (Do not let rice brown.) Add white wine, and cook 30 seconds or until most of it evaporates.
6. Add 1 cup chicken broth, and stir constantly until mostly absorbed. Add additional broth in 1-cup increments, stirring after each addition until most of the broth is absorbed. Stop adding broth when rice appears to be saturated. (You may not need all 5 cups broth.) Cook, stirring frequently, 20 to 25 minutes or until rice is tender and creamy but not mushy.
7. Stir in arugula, 1/4 cup Parmesan, remaining herbs, and any collected juices from the chicken. Place chicken on top of risotto. Reduce heat to low, cover, and cook 2 to 3 minutes or until chicken is warmed through and arugula is wilted. Add a little more chicken broth if the risotto gets too dry. Serve risotto warm, topped with chicken, tomato, and remaining Parmesan.
Kitchen Confidential: Sara's Secrets for Perfect Risotto:
The spoon: A regular spoon will work, but a risotto spoon will get the tender results you're looking for. Rice passes through the spoon's hole instead of getting mashed.
The rice: Once the rice turns glossy and translucent, it is fully coated with olive oil and butter and ready for the liquid.
The broth: Keep it hot! For maximum absorption and creamy texture, make sure the chicken broth is still hot when it's added to the risotto.