Mix the butter and brown sugar in a bowl.

Add flour and mix until homogeneous.

Keep in the fridge until hard.

In a medium saucepan, combine the butter, milk, and salt.

Heat until the butter melts completely.

Reduce the heat to low and add the flour.

Stir vigorously until the mixture leaves the sides of the pan and begins to form a stiff ball. When some of the dough sticks to the bottom of the pan, remove from the heat. Let it cool.

Add the eggs, one at a time, mixing well to incorporate completely after each addition.

Put the choux pastry in a piping bag and start piping.

Heat the milk and vanilla extract in a saucepan.

Beat the egg yolks with the sugar in medium-sized bowl.

Add the flour and cornstarch and mix again.

When the milk is boiling, pour it onto the eggs and sugar and whisk.

Put the preparation back in the saucepan.

Cook over a medium-low heat, stirring constantly, until the mixture thickens.

Add the butter and whisk until a homogeneous blend is obtained.

Pour the pastry cream into a pan and press a piece of plastic wrap onto the surface of the pastry cream to prevent a “skin” from forming.

Then, open the oven door to get rid of the steam and bake for 8-10 minutes more until the choux are brown.

Pipe the cold vanilla pastry cream inside the choux.

Sprinkle icing sugar on top.