Bring 3 1/2 cups water, 1/4 teaspoon salt, and bay leaves to a boil in a large saucepan. Stir in rice. Reduce heat, and simmer 50 minutes or until rice is tender. Remove rice from pan, draining if necessary. Discard bay leaves.
Heat pan over medium-high heat. Coat pan with cooking spray. Add leek and thyme; sauté 5 minutes. Stir in remaining 1 cup water, remaining 1/4 teaspoon salt, cooked rice, broth, potato, and pepper; bring to a boil. Reduce heat, and simmer 30 minutes or until potato is tender.
Place 2 cups rice mixture in a blender. Remove center piece of blender lid (to allow steam to escape); secure blender lid on blender. Place a clean towel over opening in blender lid (to avoid spills). Blend until smooth. Return pureed mixture to pan. Stir in cream. Cook over medium heat just until heated.