Heat oven to 180 °C.

Take half the courgette and grate finely. Sprinkle with salt, put into a colander and let drain. Wring it out, if necessary.

Put grated courgette into a bowl, mix with ricotta, cottage cheese, chopped onions, pressed garlic, mustard, beaten eggs, and salt.

Take a round baking tin (⌀ 25 cm) and grease with 2 tablespoons of olive oil. Pour frittata batter into pan.

Slice the rest of the courgette finely. Place slices on top of the dish.

Place tin in preheated oven. Bake for 30 mins at 170–180 °C.

When done, cut frittata into 8 pieces and serve hot.