Reserve garlic and 2 tablespoons drippings in Dutch oven; discard remaining drippings. Add sofrito and wine; bring to a simmer over medium. Cook, stirring and scraping up browned bits, until mixture is reduced by half, about 3 minutes. Return chicken to Dutch oven in a snug single layer; add stock, ensuring chicken is barely covered. Return mixture to a simmer over medium. While mixture comes to a simmer, bundle together leek leaves, rosemary sprigs, thyme sprigs, and bay leaf; secure with kitchen twine, and add to Dutch oven. Reduce heat to medium-low; cover and cook until chicken is tender, 45 minutes to 1 hour.