To prepare the soup, heat a Dutch oven over medium heat. Coat pan with cooking spray. Add leek to pan; cook 8 minutes or until tender, stirring frequently. Stir in broth and 1 cup water; bring to a boil. Add potato; cook 10 minutes or until potato is tender. Stir in chard, pepper, salt, and beans; cook 3 minutes or until chard wilts. Remove from heat; stir in lemon juice.
To prepare the pesto, combine cheese and remaining ingredients in a food processor; process until smooth, scraping sides of bowl occasionally. Ladle 1 cup soup into each of 6 bowls; top each serving with about 2 teaspoons pesto.