Cream butter, brown sugar, and granulated sugar together until fluffy. Beat in the egg and vanilla extract. Dissolve coffee granules in a teaspoon of hot water, then mix into the wet ingredients. Combine flour, white chocolate powder, baking soda, and salt in another bowl. Gradually mix the dry ingredients into the wet ingredients. Finally, stir in the white chocolate chips. Scoop dough onto a baking sheet lined with parchment paper. Bake at 350°F (175°C) for 10–12 minutes or until the edges are set but the center is soft. Cool before devouring!