Finely chop the garlic and shallots (or onion) and fry in a little butter or olive oil in a pan over a medium heat for 3/4 minutes.
Then add the pine nuts and toast them for 3/4 minutes. Set aside.
Preheat your oven to 180°C.
Prepare the spinach. If you are using fresh spinach, clean it and fry it for a few minutes (5 minutes max). Squeeze it gently in a sieve to extract some of the juice.
Put the spinach in a bowl, add the cheese, and mix with a fork to blend well. Then add the shallots, garlic and toasted pine nuts and mix again.
To make your filling a little more consistent, you can add 1 egg and 2 tablespoons of the flour of your choice at this point and mix in with a fork. Beat well the egg.
Season the mixture with nutmeg, sweet pepper, salt and pepper and dill if you like.
Take your puff pastry out of the fridge, line a pie dish with the pastry and prick the bottom. Brush with wholegrain mustard.
Then place your spinach and cheese mixture on top and sprinkle with grated cheese if you like.
Bake for 25 to 30 minutes, checking the pie is cooked after about 20 minutes (the pastry should brown well).
Enjoy this pie hot, warm or cold, with a small salad on the side.