Add butter to a small pot on the stove and melt over medium to low heat. Whisk constantly until the milk solids start to turn brown; turn off the stove and remove from the heat. The milk solids will continue to brown even after you remove it from the stove, so make sure to remove it from the heat earlier than you think! Set aside to cool for around 10 minutes.
Preheat oven to 350F (176C).
Mix together the dry ingredients: oats, flour, salt, baking powder, and baking soda in a medium bowl.
When the butter has cooled down, zest half of an orange to a whole orange into the butter (We like to zest the whole orange for maximum orange flavor, but it's personal preference! You can also leave this step out entirely).
Add vanilla extract, the granulated sugar, brown sugar, and whisk well.
Add the egg to the sugar and butter mixture and whisk well until everything is fully combined.
Mix together the dry ingredients and the wet ingredients until there are no dry spots. It may seem a little too wet at first; if you let it sit for about a minute or two, the flour should start to hydrate and it will thicken up. The dough should hold its shape but it should not be too firm. (If it is still very runny after 5 minutes of sitting, try putting it in the fridge for 10-15 minutes).
Optional step: chop about half of the chocolate chips into smaller pieces; we like to do this to get some variety of chocolate texture, but you don't need to do this!
Fold in chocolate chips until evenly distributed.
Spoon the mixture onto a baking tray lined with parchment paper. The mixture should make 12 cookies. We put six cookies on each tray and bake the trays one at a time for even baking in our oven, but you can bake two trays at once if you wish!
Bake for 8-10 minutes until you can see the edges start to turn golden brown. Take them out of the oven - the cookies will seem underbaked, but let them set on the tray for 1-2 minutes before transferring to a cooling rack.
Once cooled off slightly, enjoy with a cup of coffee or a glass of milk!