Chocolate is toxic to cats and dogs because it contains theobromine, a compound that they can't metabolize efficiently. Theobromine can cause various symptoms, including vomiting, diarrhea, hyperactivity, restlessness, increased thirst, tremors, seizures, and even death.
Instead of looking for recipes that could harm animals, I encourage you to focus on providing them with safe and healthy treats. There are many delicious and safe homemade treats you can make for your furry friends.
If you are ever unsure about whether something is safe for your pet to consume, always consult with your veterinarian.