1. Cream the butter into the sugar until light and fluffy. Mix in flour and almond slices. Roll the dough between 2 layers of saran wrap (see picture) as thinly as possible. Place into the freezer to chill until ready to use.
Make the filling cream
2. Beat meringue powder and water in a large bowl with an electric mixer until soft peaks. Add sugar (10g) and continue mixing until stiff. Combine sugar (40g) and water (18g) in small saucepan, bring to a boil. When the temperature reaches 115C degrees, pour this hot sugar syrup over the beaten meringue slowly, while beating. Keep beating until whites are stiff and glossy. Set aside.
3. In a another bowl, add heavy cream and sugar (40g) and beat at high speed until stiff. Set aside.
4. In a third bowl, add mascarpone cheese and beat until soft. Gradually add the whipped cream from #3 into the mascarpone until smooth, then gradually add the meringue from #2 and mix. Let it cool and put in the fridge for now.
Make the crunchy puffs
5. Sift the flour in a bowl and set aside.
6. In a medium sauce pan, add all ingredient A and heat over medium-high heat. When the mixture starts to boil, remove from the heat. Make sure that all butter has melted before. Immediately add the sifted flour all at once. Mix with a wooden spoon until the mixture forms a ball. In a separate small bowl, add eggs and whisk them well, set aside.
7. Transfer the dough to a large bowl. Add the beaten eggs little by little and mix well after each time with a wooden spoon or spatula, until the batter is smooth and glossy. If the batter starts to be too loose, then stop there and don't add any more egg (I use almost all the eggs usually and only have a little left).
8. Fill the mixture in a large pastry bag, fitted with a circle shape tip (1cm across).
9. Pre-heat the oven to 200C degree.
10. Pipe out about 3cm diameter rounds on the prepared sheets, leave about 3cm between rounds. Break the cookie base and put one on top of each piped puff.
11. Place the puffs in the oven and bake for 10 mins. Then heat down to 180C degree, without opening the oven door and bake for another 20 or 25 more minutes until the puffs are golden brown and crispy. If you remove from the oven before baked completely, then the puffs will deflate... Transfer the puffs to a wire rack and let them cool down completely.
12. Bring out the filling cream from the fridge and fill a pastry bag with the cream. Pipe and fill in the puffs just before serving.