Put beater attachments and a large bowl in the freezer for 10 minutes.
Work the flour, salt, baking powder, vanilla seeds and butter together with your fingers to a coarse textured dough. Add the sugar and rub it through.
Make a well in the dough, add the yolks, cover with the mixture and crush with the palm of your hand. Repeat until the yolks are completely incorporated. Lightly flatten the ball of dough, cover with plastic wrap and refrigerate for 1 hour.
Preheat oven to 170°C. Take the dough out of the refrigerator and work it again to soften. Flour the work surface and rolling pin and roll out dough to 1cm thick. Cut circles using 8cm pastry rings and place each biscuit in its ring on a tray lined with baking paper. Bake for 10-12 minutes, then cool for 15.
Whip the cream in the chilled bowl and put in the fridge. In another bowl, use an electric beater to beat the cream cheese, vanilla seeds, sugar, juice and zest. Fold in the cream. Spread over the biscuits, still in their rings, then refrigerate for 6 hours.
Remove the rings from the mini cheesecakes and serve immediately.