Grease the tin thoroughly with butter or margarine.

Lay the pastry sheet into the tin and press into the sides.

Cut off the excess with a knife and then press the pastry in again so that it rises up above the tin slightly to allow for shrinkage.

Put the case into the freezer to chill.

Remove the case from the freezer (the colder the better, frozen is fine!)

Line with baking parchment and fill with baking beans

Cook at 180° for 10 minutes

Remove the paper and beans and cook for a further 10 minutes

Heat the olive oil in a large frying pan

Gently fry the shallot and mushrooms for 5 minutes

Add the garlic and fry for a further minute

Cook the asparagus spears in boiling water for about 3 minutes or until just tender

Cool under running water and cut in half, keeping the tips to one side

Chop the remaining asparagus stems into dice and add to the mushroom mixture

Whisk together the cream, eggs and mustard, stir in the tarragon, add salt and pepper to taste

Pull it All Together

Increase the oven temperature to 200°C

Spoon the mushroom/asparagus mixture into the case

Top with slices of brie

Pour over the egg/cream/mustard mix

Top with the reserved asparagus spears

Bake in the preheated oven for 20 - 30 minutes until golden on top