In a food processor with a steel blade put butter, sugar, salt and flour and blend together until you receive large chunks of dough.
Add black sesame seeds and mix until it spreads evenly in the dough.
Flatten the dough between two baking papers and roll with a rolling pin to about 2-3 mm thick. Freeze for about 30 minutes to set.
Cut out small circles of about 3-4 cm in diameter. Keep the crumble circles in the refrigerator until baking.
Preheat oven to 180c degrees.
In a medium saucepan put milk, salt, sugar and butter and heat to a strong boil.
Add flour and stir while cooking, until it turns into a lump of dough.
Transfer the dough to the bowl of an electric mixer with a paddle attachment and mix on medium speed for 2-3 minutes until it cools down a little.
Add the eggs gradually while beating until dough is elastic and smooth. Check the readiness of dough by creating a "trail" with a wooden spoon in the center of the dough - if the track remains stable, add some eggs, and if it closes a bit - the dough is ready. It is important not to add too many eggs to the dough or it may become too soft and ruined.
Transfer the dough to a pastry bag fitted with a serrated 2 cm piping tip.
On a baking tray lined with baking paper pipe small cream puffs. It's important to leave some space between the cream puffs, as they will double their volume while baking.
Place a round circle of black sesame crumble over each cream puff and flatten a bit.
Bake the cream puffs for about 20-25 minutes or until the cream puffs are golden and set. Cool completely before filling.
Macha pastry cream:
In a small pot, put milk and vanilla together and heat to a boil. Meanwhile, in a separate bowl mix egg yolks, sugar and cornstarch.
Strain into the egg yolk mixture, while comparing the temperatures, the boiling milk and whisk well until combined.
Return the cream to the pot and continue to cook on medium heat while whisking constantly until thick pastry cream is created. The cream is ready when bubbles begin to form and it is boiling.
Add the matcha powder and butter and mix well until fully incorporated.
Remove from heat and transfer to a flat container. Cover the surface of the cream with plastic wrap and cool for 2-3 hours in the refrigerator until it is fully set.
When the cream is cold, whisk it until it returns to its original creamy texture.
Transfer the cream to a piping bag fitted with a smooth 1 cm piping tip and fill the cream puffs generously.
Drizzle another tiny mound of cream at the top of each cream puff (it will be used as a "glue" for the decoration).
White chocolate and black sesame decoration:
Dissolve the white chocolate in the microwave or over double-boiler.
Pour the chocolate on a baking sheet and spread to a thickness of 3-4 mm.
Sprinkle black sesame in a uniform layer.
Cool for 10-15 minutes in the refrigerator until the chocolate starts to set, but is still slightly soft.
Cut out circles of about 3-4 cm in diameter and cool in the freezer for 1/2 hour for complete stabilization.
Place a white chocolate black sesame disc at the top of each cream puff and serve.
The cream puffs at their best on the day of preparation, but you can keep them in a closed container in the refrigerator up to 3-4 days.
The puffs can be prepared without filling and kept in the freezer for up to a month in a closed container.
Instead of black sesame, you can use regular sesame seeds. The taste and appearance of course will vary accordingly.
Matcha powder can be obtained in premium tea shops.