Preheat oven to 350F and place rack in center of oven. Line baking sheet with parchment paper.
Melt the chopped chocolate with butter and instant coffee powder either in microwave or by putting the bowl with chopped chocolates on top of simmering water. Stir until all chocolate is fully melted. Do NOT leave unattended, keep stirring to retain smooth consistency. Add vanilla extract and salt and stir. Set aside to cool.
Add Egg: Add egg yolk to the melted chocolate and mix.
Mix Dry Ingredients: Add flour, baking soda and baking powder. Stop when the flour is fully incorporated. Do not over mix to avoid tough cookie.
Chill the cookie dough for at least 30 minutes
Divide and Shape: Divide the cookie dough into 12 portions. I used kitchen scale for even size, you can just eye-ball it if you do not have kitchen scale. You can also use 1 teaspoon to measure each portion. Roll each ball in palm of your hand to make it moist.
Coat with Granulated Sugar: Roll each piece in the granulated sugar, making sure each ball is completely coated, with no chocolate showing through.
Coat with Confectioners Sugar: Roll each piece in the confectioners sugar next, making sure each ball is completely coated, with no chocolate showing through. Place the sugar-covered balls on the prepared baking sheet, spacing about 2-3 inches apart.
Bake the Cookie: 10 grams size cookie (approximately 1 teaspoon or 1-inch): Bake for about 6 minutes or just until the edges are slightly firm but the center is still soft and the outer shell starts to crack (For moist chewy cookies do not over bake. Over baking these cookies will cause them to be dry.)
Top with Chocolate: Remove from the oven and top each cookie with chocolate kisses. Return to the oven for another 1 minute.
Let Cool: Remove from oven and leave on the pan to cool until no longer soft to transfer in a cooling rack. These cookies are very fragile so be very careful when transferring it.