How to make
Thaw the puff pastry at room temperature for about 30 min. or leave it in the fridge overnight.
Make the cream by beating the butter with the powdered sugar to a fluffy white consistency. Gradually, add the mascarpone, without stopping to beat, until you get a smooth cream.
Cover with foil and put it in the fridge. Preheat the oven to 430°F (220 °C) or 390°F (200 °C) with the fan on and cover the bottom of a shallow oven dish with baking paper.
Lay out the puff pastry onto a lightly floured work surface, cut it in 2 equal parts with a knife. Cut out a circle from each one, as large as the puff pastry allows. Use a suitable plate to help you. With a thin-walled glass, cut out the middle, so that you get something like a large donut.
Smear one of the puff pastry rings with beaten egg yolk and cover it with the other one, press along the edges of the puff pastry so that they don't separate during baking. Smear with beaten egg again and sprinkle on the sliced almonds. Bake to a golden brown. Leave it to cool completely on a cooking grid and cut it laterally through the middle with a sharp knife.
Put the cream in a pastry bag and spray it on the bottom half of the cut puff pastry ring. Garnish with fresh raspberries and cover with the upper half of the puff pastry. Before serving, sprinkle it with powdered sugar and decorate with mint leaves.