How to Make It
Preheat oven to 400°.
Heat oil in a large Dutch oven over medium heat. Add onion, garlic, and thyme; sauté 6 minutes. Stir in miso; cook 1 minute. Add 1 cup stock, stirring until miso dissolves. Stir in remaining 3 cups stock. Lightly mash 1 cup beans. Add mashed beans, remaining 1 cup beans, salt, bay leaves, and black beans to stock mixture in pan; bring to a simmer. Reduce heat, and simmer 15 minutes. Remove pan from heat; discard bay leaves. Stir in spinach until wilted.
Arrange bread slices on a baking sheet coated with cooking spray. Bake at 400° for 5 minutes or until toasted. Combine tomato and chives in a bowl. Divide tomato mixture evenly over bread. Place about 1 1/2 cups soup in each of 4 bowls; top each serving with 2 topped bread slices.