Kue choc chip oatmeal mentega coklat

Bahan-bahan (22 porsi)

• 150 g /10 tbsp unsalted butter (, cut into 1cm / 1/2" cubes)
• 1 cup flour (, plain/all-purpose)
• 1 1/2 cups rolled oats ((not quick or steel cut))
• 1 tsp baking soda (bi-carb) (, sifted if lumpy)
• 1/8 tsp cooking/kosher salt
• 1 cup brown sugar ((tightly packed))
• 1 large egg (, at room temperature (~55g/2oz))
• 1 tsp vanilla extract
• 200 g / 7 oz 70% dark chocolate block, I use Lindt ((Note 1, sub 1 cup / 200g chips))