boneless skinless chicken breast, cut into 1/2 inch cubes • medium onion • 1⁄2 teaspoons garlic powder • vegetable oil • cans great northern beans, rinsed and drained • can chicken broth • salt • oregano • ⁄2 teaspoon pepper • ⁄4 teaspoon cayenne pepper • sour cream • ⁄2 cup whipping cream •