Preheat the oven to 325 degrees.
Line baking sheets with parchment paper or baking mats.
Melt the butter and chocolate together. Cut the butter into large chunks and break the chocolate into squares. I use the microwave, heating it in 30 second increments. Stir between each heating until fully melted.
Set the butter and chocolate to cool down for a few minutes.
In a large bowl, whisk together the flour, baking powder, and baking soda. Set aside.
Transfer the butter and chocolate mixture to a large bowl.
Add the granulated sugar to the butter and chocolate mixture. Stir until fully combined.
Add the egg and stir until fully incorporated.
Add the vanilla and mix.
Add the dry ingredients to the wet ingredients. Don't over mix, just make sure there aren't any pockets of flour.
Prepare two small bowls for the topping, one for the granulated sugar and one for the powdered sugar.
Scoop out about a tablespoon of cookie dough and roll it into the ball.
Roll the ball first into the granulated sugar and then into the powdered sugar.
Put the prepared cookie balls onto the trays, leaving a decent space in between.
Bake for about 15 minutes. In this particular case, it is better to bake only one sheet at a time.
Let cool on the tray for about five minutes and remove to a wire rack.