1. In the bowl of a stand mixer place soft butter and both sugars. Using the paddle attachment beat the mixture on medium high until very light and creamy. 1 full minute. Alternatively, beat with an electric hand mixture for the same amount of time.
2. Add egg and vanilla. Continue beating for another 2-3 minutes to aerate the dough.
3. In a separate bowl whisk together the flour, baking powder, baking soda and salt. Add to above and mix on low until almost but not quite incorporated. Add chocolate and finish mixing just until all the flour is incorporated.
4. On a cookie sheet lined with parchment paper scoop the dough into balls about the size of a golf ball. Sprinkle with salt if using. Cover with plastic wrap or put in an airtight container and refrigerate for at least one hour.
5. Pre-heat oven to 350 degrees F. Place rack in center of oven. On a cookie sheet lined with parchment paper place dough balls 2"-3" apart. Bake one tray at a time for 18-20 minutes until the edges are golden brown. Let cool on tray for 5 minutes before transferring to a cooling rack. Repeat with remaining trays.