Preheat the oven to 350°F.

1. For the pastry, mix the butter and powdered sugar together using a robot.

2. Add the egg, then the flour, and mix. Add the red food coloring until the desired color is achieved.

3. Shape the pastry into a ball, wrap it in plastic wrap, and refrigerate for 40 minutes.

In the meantime, prepare the pastry cream:

4. Mix the egg yolks and sugar together, add the cornstarch, and dilute completely. Add the vanilla extract and red food coloring.

5. Bring the milk to a boil. Pour the boiled milk over the egg yolk mixture and whip vigorously to avoid lumps.

6. Pour this mixture back into the saucepan and bring to a boil again. Set aside off the heat.

7. Roll out the pink pastry and fill the mold, then fill the tart with cooled pink pastry cream up to half height.

8. Bake for 20 to 30 minutes and let cool completely on a rack.

9. Arrange the blackberries in tight rows and enjoy!