Heat oil for the topping in a pot at medium-low heat, add onion and garlic. Cook until very soft (about 10 minutes).
Add ají amarillo paste (if using), cook for another 5 minutes, stirring often.
Add polenta, milk and salt. Simmer for 20 minutes, stirring often.
Take pot off the heat, let cool down.
While the polenta mix cools down: preheat oven to 180°C (160°C fan-forced) and heat oil for the filling in a pan at medium-low heat.
Add onion and garlic to the pan. Cook until very soft (about 10 minutes).
Add ají panca paste or tomato paste, cook for another 5 minutes, stirring often.
Add beef mince and cook until browned.
Season with cumin, oregano, salt and pepper. Turn heat off and mix in sultanas and olives.
Whisk eggs and mix with topping.
Spread filling in a baking tray, top with polenta mix.
Bake for 15-20 minutes or until the topping looks golden-brown.
Serve with a green salad.