Preheat your oven to 350°F (175°C).
In a mixing bowl, cream together the softened butter, powdered sugar, and brown sugar until smooth.
Add the egg and vanilla extract, mixing until well combined.
Dissolve the instant coffee granules in warm water and add to the mixture.
In a separate bowl, whisk together the flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Using a cookie scoop, drop dough onto a baking sheet lined with parchment paper.
Flatten each cookie slightly with the back of a spoon.
Bake in the preheated oven for 10-12 minutes or until the edges are golden.
Remove from the oven and let cool on a wire rack before dusting with powdered sugar.