Preheat oven to 350°F. Line baking sheets with parchment paper or silicone liners.
In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
Using an electric mixer on medium speed, combine both sugars and the butter. Beat until light and fluffy (about 3 minutes).
Combine the water, egg, Kahlua, and vanilla. Add to the sugar/butter mixture, beating until well blended.
With the mixer on low speed, gradually add the flour mixture until just combined. Stir in the chocolate chips, white chocolate chips, and pecans.
Drop the dough by tablespoonfuls onto the baking sheets. Bake for 12 to 14 minutes, or until set and beginning to brown around the edges. Cool on the pan for 1 to 2 minutes. Then, remove to wire racks to cool completely.
Notes
*Depending on humidity and the brand of cake flour used, you may need to add up to another 1/4 cup of flour.
**Lightly beat one large egg, and use half of that, which is about 2 tablespoons.