Beat together the eggs, milk, GiNiT Sage and chilli (if using), set aside until the veggies are cooked.
Put the oven shelf at the highest position that will accommodate your oven-safe frying pan or cast iron skillet, preheat the grill to 180˚C.
Heat a cast iron skillet or oven-safe frying pan with the butter over medium heat. Add onions, sauté until light golden. Add garlic and mushrooms, stir to combine and cook for 2 -3 minutes. Add the tomato and bell pepper, cook for additional 2-3 minutes, stirring to ensure even cooking. Flatten the ingredients out evenly in the pan and pour over the egg mixture, sprinkle over the feta and mozzarella cheese. Turn the heat to low. When you see the egg setting at the edge of the pan, turn off the heat, and place the pan under the griller. Cook until cheese starts to brown and the egg is fully set. If required, move the pan to ensure even browning of the frittata.
Notes
Serving suggestion:We enjoyed our frittata with chopped fresh parsley and coriander sprinkled over the top and a few fresh cherry tomatoes on the side.