Heat large deep skillet on medium-high heat. Add orzo; cook and stir 3 minutes or until lightly browned.
Pour in stock. Bring to boil. Reduce heat to medium-low; cover and simmer 10 minutes.
Stir in Seafood Sauce, shrimp and tomatoes. Cook, uncovered, 5 minutes on medium-high or just until shrimp turn pink and tomatoes begin to burst, stirring occasionally. (Add more stock or water as needed to keep from scorching.) Stir in spinach just until wilted.