Preheat the oven to 350°F. Line 3 large cookie sheets with parchment paper. Set aside.
In a mixing bowl, sift together the flour, baking powder, salt and baking soda. (A whisk works perfectly)
In a medium-size mixing bowl using an electric mixer, cream together butter, light brown sugar, granulated sugar and vanilla. Beat on medium for 3-4 minutes or until light and creamy.
Add eggs one at a time beating well after each addition. Stop and scrape the bowl as needed.
Lower the speed of the mixer. Add sifted dry ingredients gradually, beating well after each addition. Stop and scrape the bowl periodically. The dough will be thick.
Mix cubed candy into the dough by hand.
Use a 2 oz ice cream scoop to divide the cookie dough. Place onto the parchment paper at least 2-inches apart. Depending on size of pans used about 8-10 cookies/pan.
Bake for 12-14 minutes.
Cool on the pan for 10 minutes, then remove to a cooling rack to cool completely.