In a small saucepan (don't use a dark saucepan because you won't be able to see the browning of the butter), melt the butter over medium low heat. Continue cooking until butter is an amber color and butter solids are browned. You'll smell a nutty aroma. Be careful not to burn the butter. Remove from heat and pour browned butter into a large bowl to cool.
Add malt powder to the browned butter and stir to remove any lumps. The mixture should be smooth. Let cool for several minutes, then add brown sugar and granulated sugar. Stir for a few minutes to allow the mixture to cool even more. Once it has cooled down, but still warm, add the egg, egg yolk, and vanilla then stir well for a few minutes to incorporate.
Add dry ingredients, and stir until just combined. Add chocolate chips and make sure they're evenly distributed. Scoop batter onto two cookie sheets covered with parchment paper (about two tablespoons of dough per cookie) and place sheets into the fridge for 30 minutes.
Preheat oven to 375 F. Bake cookies for about 10 minutes or until edges are lightly browned. Allow to cool for a few minutes on the baking sheet then transfer to a cooling rack and allow to cool. Enjoy!