Heat oven to 350℉/177℃.
Line sheet pans with parchment paper. Set aside.
With an electric mixer, beat butter and sugar until creamy.
Beat in egg, egg yolk, and vanilla.
Add oatmeal.
Beat until combined.
Stir in flour, baking powder, and baking soda.
Fold in chocolate chips and granola.
Use a medium cookie scoop to portion dough onto prepared pans, about 6 cookies per pan.
Press each cookie down slightly.
Bake for 14 minutes, or until edges are starting to brown.
Cool on pans.