The pastry cream:
Heat the milk in a saucepan.
In a bowl, mix together the egg yolks, sugars, and cornstarch.
Gradually add the hot milk to the bowl and whisk until smooth.
Return the mixture to the saucepan and bring to a boil, stirring constantly, until it thickens.
Remove from heat, add the butter, and mix well.
Cover the saucepan with plastic wrap and let it cool completely.

The dough:
In the mixing bowl, using the dough hook, combine all the ingredients (except the butter) and knead for 10 minutes, or until the dough is smooth and elastic.
Cover the bowl with plastic wrap and let it rise for 3 hours at room temperature.

Roll out the dough into a square, 1 cm thick, on a floured surface.
Place the butter in the center of the square and fold the 4 corners to the center.
Roll out the dough into a rectangle, 3 times as long as it is wide, and fold it in the following way:
1/3 over 2/3, then 3/3 over 1/3.
Cover the dough and refrigerate for 30 minutes before repeating these steps 3 times.
(Every time you roll out the dough, the edge of the dough should be on your right, as if you were opening a book)

Remove the dough from the refrigerator and roll it out to a thickness of 3mm.
Spread the pastry cream over the dough and sprinkle with raisins.
Roll up the dough and cut into 12 slices, 2 cm wide.
Place the slices on baking sheets lined with silicone mats, flattening them slightly with the back of a spatula.
Cover and let rise for 2 hours 30 minutes.

Preheat the oven to 420 F (215 C).

Beat the egg and brush the small breads with it.
Bake for 15-20 minutes, or until golden brown.
Let cool on the baking sheets.