Into a large mixing bowl, sift flour, cocoa powder, baking powder, soda, and salt. Mix well and set aside.
In another large mixing bowl, beat the butter with sugar until white and fluffy. You can also use a stand mixer with a paddle attachment.
Then, add the food coloring and beat until the mixture has a homogenous color. Add an extra 1-2 teaspoons coloring, if desired, and beat again.
Add the egg and vanilla and beat until incorporated.
Add the dry mixture to the wet one and mix just until no dry ingredients are left. Add the white chocolate chips and mix again. Cover with plastic wrap and refrigerate for 15 minutes.
Meantime, preheat the oven to 180C/355F and line a baking tray with parchment paper.
Take out the dough and form 16 even balls from it (around 45g each). You can use a scoop or do it by hand.
Place on a baking tray leaving enough space in between. The cookies will spread during baking. If all balls don’t fit on your tray, bake in two batches.
Bake for 12-13 minutes or until spread and dry on the surface. Don’t overbake as the cookies can dry out too much.
Remove from the oven and leave to cool down for at least 5 minutes on the tray without touching them. Then, transfer onto the cooling rack to cool down completely. Repeat the process with the second batch and serve.