For the crispy crust
- Blend the margarine (or butter) until soft.
- In another mixing bowl, put the flour together with the Zùsto and the sifted cocoa powder. Add this to the margarine and knead with your hands to form a dough ball. It will feel a little dry at first, but just keep kneading and it will be fine!
- Take 2 sheets of baking paper and place the dough ball on them. Roll it out between the sheets of baking paper so the dough is a few millimetres thick. Allow the whole thing (dough + baking paper) to rest in the freezer for half an hour while you make the choux batter.
For the choux buns
- Place the baking paper on the baking tray and preheat the oven to 180°C.
- Place the milk, water, margarine, instant coffee and salt in a saucepan. Allow the margarine to melt completely and wait for it to bubble slightly. Remove the pan from the heat and freely add the flour. Mix with a wooden spoon to form a dough ball. Place over a medium-high heat again. The dough ball will now sizzle slightly. Turn the dough ball over a bit until the bottom begins to lightly burn (there will be a crust at the bottom of your saucepan). This is a good sign and means it is time to remove it from the heat. Put the dough ball in a bowl and allow to stand for a minimum of 15 mins before adding the eggs
- Add the eggs one by one (make sure your dough is no longer warm, or you’ll end up with an omelette :)). Make sure to mix it well between adding each egg.
- Place the batter in a piping bag and cut a 1 cm opening. Pipe firm peaks onto the baking tray. The peaks I made were 5.5 cm tall because that was the size of my dough cutter. Although these do end up being giant choux buns! :).
- Remove the dough from the freezer and cut out rounds (using the cutter) to the size of the piped peaks. Place a piece of dough on top of the buns.
- Bake the choux buns for about 18 mins in a preheated oven. Want to check if they are done? Remove one from the oven and place it on a cooling rack. Does it collapse after about 30 seconds have elapsed? If so, the buns need cooking for a little longer and so continue to bake them for a few minutes longer. If it stays upright, you can remove the rest of them.
- Allow the buns to cool completely on a cooling rack.
For the mocha batter
- Whip the cream so that it becomes whipped cream.
- In another mixing bowl, mix the mascarpone together with the Zùsto.
- Dissolve the coffee in 1 tbsp hot water and add to the mascarpone mixture. Mix until the coffee is fully mixed into the batter.
- Add the whipped cream to the mascarpone batter and then on a low speed, briefly mix the whipped cream into the batter.
- Once the buns have completely cooled, you can cut off their “hats” with a sharp knife (or make it even easier on yourself and use scissors!). Put the mocha batter in a piping bag with a serrated nozzle and pipe swirls of batter into the buns. Cover with the hat.