Preheat your oven to 350°F (175°C).

Finely chop the onion and bell pepper, then grate the zucchini. Sauté these vegetables in a skillet over medium heat for 5 minutes.

In a large mixing bowl, combine the sautéed vegetables with the ground meat, tomato sauce, tomato paste, salt, and pepper. Mix gently.

Transfer the meat mixture onto a lined baking sheet and shape it into a brain form.

Bake the Brain Meatloaf in the preheated oven for 55 minutes, checking for doneness with a meat thermometer.

Remove from the oven and let it rest for 10 minutes before slicing.