Place the butter in a mixing bowl, then add the sugar and vanilla, if using

Mix together on high speed for several minutes.

Add the egg and mix briefly - until combined.

Set aside an equal half of the dough into a second bowl - for me it was 178 g.

To one portion of the dough set aside, add flour and baking powder - mix briefly - until combined.

If the dough does not want to combine into a uniform mass, knead it briefly with your hands.

To the second portion of dough, add red food coloring.

Add flour, baking powder, and cocoa and briefly mix the dough into a uniform mass.

Scoop equal portions of both doughs with a teaspoon - for me these were "heaping" portions - about 27 g each.

Divide the dough into three smaller portions to get a total of 6 pieces - 3 white and 3 red.

Alternate sticking the pieces of dough together to create a zebra pattern.

Finally, carefully roll the dough in your hands into a marbled ball.

You should get 12 large balls.

Put the cookies in the fridge - or place them on the balcony for about 30 minutes.

Meanwhile, coarsely chop the white chocolate.

Preheat the oven to 180 ℃ (top/bottom heat) or 170 ℃ (fan-assisted).

Arrange the chilled cookies on a large baking sheet lined with parchment paper - leave ample space between them.

Gently flatten each cookie with your hand.

Sprinkle the top of the cookies with white chocolate and gently press it down.

Place the baking sheet in the preheated oven and bake the cookies for 10-12 minutes.

Immediately after baking, the cookies will still be very soft, so wait about 10 minutes before removing them from the baking sheet.