Heat oil in a medium saucepan over medium-high heat.
Add onion; cook 5 minutes or until softened, stirring.
Add garlic and thyme; cook 1 minute, stirring.
Add beans, water, tomatoes, and broth. Increase heat to high until stew begins to bubble. Reduce heat; let simmer 5 minutes, breaking up tomatoes with a spoon.
Add more water, if needed.
Add spinach, stirring until wilted.
Add chicken; cook 2 minutes. Season with salt and pepper.