Vegetarian

Heat a large non-stick frying pan over low heat
Cook the sliced onion slowly in the olive oil and butter until soft but not brown (about 15 minutes)
Add the potatoes, cover and cook 15–20 minutes, stirring occasionally
When potatoes are soft and onion shiny, crush two garlic cloves and stir them in
Beat the eggs and pour them into the pan, stirring to combine
Cover and cook gently about 20 minutes until edges and base are golden and top mostly set
Slide the tortilla onto a plate, place another plate on top, invert and slide it back into the pan to finish cooking
Transfer the cooked tortilla to a plate and scatter with chopped parsley
Slice the baguette and warm the slices
Stab the warm slices with a fork and rub them with the remaining garlic
Pile grated vine tomatoes on the slices and drizzle with olive oil