1 ⅓cups(283g)packed light or dark brown sugar (or a combo)
1large egg yolk
¾cup(64g)sweetened or unsweetened coconut flakes
1 ½ to 2cups(255 to 340g)semisweet or bittersweet chocolate chips
Preheat oven to 350 degrees F. Line a metal 9X13-inch pan with parchment and lightly grease with cooking spray (see note for other types of pans).
Add the oats, flour, baking soda, and salt to a blender and pulse until coarsely blended. The texture of the oats should be finer than quick oats but not as fine as flour. Set aside.
To a large bowl, add the melted butter, brown sugar, egg, egg yolk, and vanilla and stir with a wooden spoon or rubber spatula until the ingredients are well combined and the batter lightens a bit in color.
Add the dry ingredients, coconut, and chocolate chips and mix.
Press the batter evenly into the prepared pan. Bake for 20 minutes until set around the edges but still slightly soft in the center. It's ok if you need to add additional baking time, just keep an eye on the bars - they are better just slightly under baked.
Pan: I prefer to use a light colored metal baking pan for bar cookie recipes like this. Glass pans, ceramic pans and dark coated pans bake differently. If using one of those pans, try decreasing the oven temperature by 25 degrees.Butter: I use salted butter. To take these bars up a notch, try browning the butter. Let it cool to just slightly warm room temp before using in the recipe.