Oatmeal Chocolate Chip Cookies

I've been looking for a good plain-old chocolate chip cookie recipe, and I think I've found it... well, it's chocolate chip oatmeal, but I like the folkloric texture oatmeal gives. And it's good for you... as chocolate is.

MAKES : 32 x 1oz

⅔ cup (5.33 oz/151gr) butter, room temperature 
1 cup (164g) brown sugar
1 egg
2 tsps vanilla
½ tsp baking powder
½ tsp baking soda
¼ tsp salt
1½  cup (150g) rolled oats
1½ cup (260g) chocolate chips

1 cup flour
(optional) ½ cup (56g) walnut pieces
(optional) pinch of cinnamon

1. In a large mixing bowl beat the butter and sugar until pale and fluffy. Whip in the egg and vanilla, then the baking powder, baking soda and salt. Add the rolled oats and chocolate chips and mix until well combined. If using the Optional walnuts and cinnamon, add them with the chocolate chips.
2. Finally, add the flour, mixing only until combined.
3. Wrap and put in the refrigerator to rest for 1 hour and up to 72 hours.
4. Pre-heat oven to 375°F.
5. Drop a Tablespoon of dough (1oz) per cookie on a parchment-paper lined cookie sheet. Flatten with your hand and bake 10 to 12 minutes.
6. Transfer to racks to cool.