Preheat oven to 200°C | 400F | gas 6. Cut out three circles from baking paper using free hand. Roll out the short crust pastry and cut to the size of the circles. Prick them lightly with fork and place on a lightly greased or baking paper covered baking sheet. Place short crust pastry circle in center and bake until golden brown, for about 12-15 minutes.
Cut out six same-size circles from the puff pastry, place on baking paper. Prick with fork. When the shortcrust pastry has cooked, remove and place the three puff pastry circles in oven and bake until risen and golden brown about 10-13 minutes. Remove from oven and allow the pastry bases to cool completely.
Remove the dispenser from the box including the charger holder and two dispenser tips. Unscrew the top off the dispenser, then screw on the tip of your choice (straight or tulip) while holding in place the valve stem under the cap. Be sure to screw the tip on tightly. Make sure that the gasket (also called the O-ring) is firmly in place on the underside of the head.
Pour in one pint of well-chilled heavy whipping cream in a pint dispenser. Do not exceed recommended amount. Add powdered sugar and vanilla. Screw the top evenly and firmly onto the bottle. Do not cross-thread. Place a nitrogen oxide cartridge in the holder with the small end visible. Twist charger holder onto head until gas is released. A slight hissing sound will be heard. For a pint dispenser, use only one charger per filling. For a quart dispenser, use two chargers per filling.
Shake the dispenser 4-6 times. Turn the dispenser upside down. This is important, otherwise gas will escape and a proportionate amount of whipped cream will not be released. To assemble, spread one third of the plum jam on the shortcrust base, and one third on each of two puff pastry circles. Top the plum filling on the discs equally with whipped cream by dispensing cream as needed by pressing on the lever. Layer the two cream and plum covered puff pastry shells in layers on the shortcrust base
Finish with the third puff pastry shell and sprinkle this with confectioner's sugar to decorate.
When the canister is empty, simply discharge any remaining pressure in a sink or wastepaper basket and unscrew the top. The small brush that is included is useful for cleaning the tips. Do not put dispensers in a commercial dishwasher.