To make pastry cream:
Split a vanilla bean lengthwise, using a back of knife to scrape the seeds. In a medium saucepan, combine milk with the vanilla bean and seeds and lemon rind. Bring to a boil, then remove the lemon rind and vanilla bean.
In a medium bowl, whisk the egg yolks. Add the sugar and flour and whisk well. Before adding the egg yolk mixture to milk, temper it by whisking in some of the milk to the yolk mixture. Pour it all back into the milk saucepan. Bring to a boil and cook at a boil for 2 to 3 minutes then remove from stove top and cool.
Cut the puff pastry into 3 by 3-inch squares. You should have 24 pastry squares in total. Bake according to package directions until golden brown and crisp. Remove from the oven and cool.
Place 1 square of puff pastry on a plate. Top with a layer of pastry cream. Top with raspberries and a small dollop of pastry cream. Repeat to make 1 more layer, ending with a puff pastry square on top. There should be 3 layers of puff pastry and 2 layers of pastry cream and raspberries in each stack.
Repeat with the remaining ingredients.
Recipe courtesy of Chef Fabrizio Batola, Hotel Villa D'Este, Italy