Turn on the oven to preheat to 190 degrees. Cover a round heat-resistant form with a diameter of about 23 cm with parchment.
Heat vegetable oil in a large skillet over medium heat. Pour chopped onions, green peppers, and garlic into the pan, cook, stirring occasionally, until vegetables are soft, about 5-8 minutes.
Put the mixture from the pan into the prepared dish, along with the tomato, olives, potatoes, sausages, and chili. Mix everything well and sprinkle with chopped cheese on top.
In a small bowl, beat eggs and milk. Add cumin, oregano, paprika, salt, and black pepper. Pour this mixture into an ovenproof dish with vegetables.
Place the dish in the oven and bake for about 30 minutes, until golden brown. Serve the potato casserole with arugula (arugula).