Line a large baking sheet with a silicone baking mat, set aside.
In a large mixing bowl add the butter and sugars. Using a hand or stand mixer cream the butter and sugars together until fluffy.
Add in the large egg, vanilla and mix until combined.
Add the flour, baking powder, and salt. Mix until combined. The dough might seem to be in crumbles as mentioned above.
Pour in the chocolate chips and pecans (if using) and use your hands to mix them in. This will bring the dough together. Be gentle though. We don't want to compact the dough too much. We want to keep it as airy as possible.
Divide the dough into 6 pieces. Gently form into cookie form. Place on the baking sheet.
Chill the cookie dough for at least 30 minutes. Preheat the oven to 375 during this time.
Bake the cookies for about 16-18 minutes. The outside will be golden brown.
Let the cookies cool on the baking sheet for at least 5 minutes, then remove to a wire rack to continue cooling. The cookies need to cool prior to serving. They are best at room temperature.