Preheat the oven to 180 °C.
Prepare a cake tray with 8 paper cases.
Slice the mushrooms, chop the courgette into small pieces and fry in the butter until fully cooked.
In a bowl, lightly whisk the eggs and milk using a fork.
Finely grate the parmesan.
Add the mushrooms, courgette, parmesan and herbs into the egg mix and stir.
Pour the mix into the paper cases up to 80% full (they will rise slightly).
Cook in the oven for 20 minutes at 180 °C.
Eat warm or leave to cool on a wire cooling rack.