Pre-heat oven to 350°F.
Line large baking sheets with parchment paper.
Cream together butter and sugars for 2-3 minutes.
Mix in egg and egg-yolk and vanilla until combined.
Add baking powder and salt to the bowl and mix briefly.
Pour in flour and stir just until all flour is incorporated.
Measure in chocolate chips and pecans and mix very briefly to combine.
Place 2-3 tbsp dough balls about 2 in. apart on lined baking sheets.
Lightly press down on dough balls.
Bake for 12-14 minutes, until very lightly browned. Cookies will still be soft upon cooling so be careful not to overcook.