Preheat oven to 180°C (350°F).

Heat a medium skillet over medium heat and add olive oil. Add the onion and sauté until softened, then add the red and green bell peppers and cook for a few more minutes.

Add the sucuk slices and cook until slightly browned.

In a bowl, whisk together the eggs and milk, then season with salt and pepper.

Pour the egg mixture into the skillet over the sucuk and vegetables, distributing evenly. Sprinkle the shredded cheese over the top.

Transfer the skillet to the preheated oven and bake for 15-20 minutes, or until the frittata is puffed and golden.

Remove from the oven, let it rest for a few minutes, then garnish with fresh parsley or chives. Slice and serve.