In a small bowl, mix flour, hojicha powder, baking powder, baking soda and salt. Set aside.
In a large bowl, use an electric mixer to beat the softened butter until very creamy and pale in color. Add the brown sugar and mix for about 3 minutes.
Add the egg and milk and mix on low speed until well blended. Add the first flour mixture and mix gently. Then add white chocolate pieces and finish mixing with a spatula.
I recommend that you leave the dough in the fridge for at least 30 minutes, or even overnight, to chill so that you get thick, chewy cookies after baking.Preheat the oven to 180°C and line a baking sheet with parchment paper. Set aside. Using a large ice-cream scoop, shape the cookie dough into balls. Place the dough on the lined baking sheet, leaving a 5 cm space between each ball to allow it to spread.
Bake the cookies for 10 to 12 minutes. About 2 minutes before the end of baking time, place a few pieces of white chocolate on the top of each cookie to obtain perfect cookies.
Let the cookies cool on the baking sheet for 5 to 10 minutes before carefully transferring them to a wire rack to cool completely.