Whisk together flour, baking powder, baking soda, salt and set aside.
Beat butter and sugars until creamy. Add the egg, egg yolk, and beat until light and fluffy. Add the vanilla extract and beat.
Add the flour mixture to the butter mixture and mix until just combined.
Add the chocolate chips and toffee bits and stir until combined. Using a 1/4 cup amount cookie scoop as a guide, scoop the dough into a ball and place them on a platter. Cover with a piece of plastic wrap and chill for 1 hour to 2 days. I recommend to chill 2 days for the best texture.
Preheat the oven to 375˚F. Line a cookie sheet with a parchment paper.
Place chilled cookie dough balls on a cookie sheet, placing apart. Bake for 12-14 minutes or until the edges of cookies turn light golden. Rest the cookies in a sheet for 2-3 minutes, then transfer them to a cooling rack and cool completely.