Melt the butter, pour it into the bowl of a stand mixer, and let it cool until it is no longer hot but is still liquid.

Add the brown sugar and granulated sugar. Mix for about 4 minutes, stopping once or twice to scrape the sides and bottom of the bowl.

Mix in the whole egg until combined, then add the egg yolk and mix again.

Stir the baking soda into the hot water until dissolved. Add it to the butter mixture with the vanilla and mix briefly.

In a separate bowl, whisk together the all-purpose flour, cake flour, baking powder, cinnamon, and salt.

Add the dry ingredients to the wet mixture in a few additions. Mix only until no dry flour remains.

Fold in the white chocolate chips, semi-sweet chocolate chips, and chopped pecans with a spatula or wooden spoon.

Scoop the dough onto a parchment-lined baking sheet. Cover and refrigerate for at least 3 hours or overnight.

When ready to bake, heat the oven to 350°F and line baking sheets with parchment paper.

Arrange the chilled dough portions about 2 inches apart on the prepared baking sheets.

Bake for 10 to 12 minutes, until the edges are lightly golden and the centers still look a little soft.

Let the cookies rest on the baking sheet for a few minutes, then move them to a wire rack to finish cooling.