Spray the inside of the 11*13 pan with nonstick spray
Place in parchment paper (cut the corners on a diagonal so it lays flat)
Lightly spray with nonstick and set aside.
Preheat the oven to 350 degrees
Add oats, flour, baking soda, and salt to a food processor and pulse until oats are finely chopped, omit this step if you like the texture of the oats as is.
In a large bowl, melt the butter.
Add in brown sugar, egg, egg yolk, and vanilla. Stir to combine.
Add in the dry ingredients until incorporated
Mix in the chocolate chips
Pour batter into the pan, spread it out to the ends, it will look like there is not enough batter to cover the bottom of the dish, just make it as even as possible.
Bake for 18-20 mins or until the edges are golden brown.
Remove from the oven and let for at least 30 mins prior to removing the parchment paper from the pan and slicing the bars.
Bars can be stored for up to 7 days in an airtight container, they could also be frozen.