1. Melt butter in a large saucepan over medium-high heat. Add onion, 1 tablespoon sage, and garlic to pan; sauté 4 minutes or until lightly browned. Add pepper and cumin; sauté 1 minute. Stir in 1/2 cup stock; cook 1 minute, scraping pan to loosen browned bits. Combine onion mixture, remaining 2 cups stock, beans, and pumpkin in a blender; process until smooth. Return stock mixture to pan. Stir in milk and salt. Bring to a simmer; cook 5 minutes, stirring occasionally. Stir in vinegar.
2. Combine remaining 1 tablespoon sage, spinach, and remaining ingredients in a mini food processor; process until smooth. Ladle about 2/3 cup bisque into each of 8 bowls; top each serving with 2 teaspoons pesto.