Begin by preheating your oven to 325 degrees and greasing a large cookie sheet.
In a large mixing bowl combine the flour, bread flour, dark brown sugar, sugar, powdered milk, salt, and baking soda.
Give the dry ingredients a good stir with a large spoon.
Next, soften your butter. I recommend using your microwave, I did only about 10 seconds. Your butter should still be solid but softened just a little so it can be easily mixed into your dough.
Add the butter in with the dry ingredients.
Add the egg, molasses, vanilla and mix with a hand mixer until well mixed. Dough may seem crumbly at first but mix until it becomes more cohesive.
Stir in the chocolate chips with a large spoon.
Use a large cookie scoop (about 2.5 to 3 tbsp) to form your cookies.
Chill the dough for 1 hour in your fridge.
Bake at 325 degrees for 14 to 16 minutes. Let them rest for 10 minutes on the baking sheet.