Preheat the oven to 250 degrees hot air. Let the butter for the tiger print / croustillant come to room temperature. For the choux batter; Bring the milk together with the water, butter, salt, sugar and invert sugar to the boil over medium heat. dissolve in 1 liter of water and then add lemon juice.For this recipe you can also use caster sugar instead of invert sugar.) Then add the flour and reduce the heat to low. Stir the mixture dry with a spatula. Once the mixture feels like a dry ball of dough, place in food processor or mixing bowl and mix with a dough hook at medium speed. Then add the eggs one at a time, adding the next egg only when the batter has fully incorporated the egg. Spoon the batter into a piping bag with a smooth nozzle if desired.
Line a baking tray with baking paper, grease the baking paper with 20 grams of melted butter and dust with flour (By greasing the baking paper with melted butter and then dusting with flour, you ensure that the choux does not spread). Make an impression in the flower with a round object so that the puffs have the same nice round shape. Pipe the choux batter into a ring shape on the baking tray, making sure you make two layers so that the choux is nice and high.
Preheat the oven to 250 degrees hot air.
Place the croustillant dough between two baking papers and roll out with a rolling pin into a thin sheet. Then let it set briefly in the freezer for convenience. Cut circles out of the croustillant with the same round object that was used for the shape of the puffs. With a smaller round shape, cut another circle from the center to create a ring shape and place the ring of croustillant on the choux batter.
Slide the puffs into the preheated oven and turn the oven off. Leave the puffs in it for 10 minutes. Then turn the oven to 160 degrees and let the puffs bake for another 10 minutes.
The puffs should be really golden brown before you take them out of the oven. Do not open the oven while baking or they will collapse.