Preheat your oven to 350°F (175°C) and line a 9x13-inch baking pan with parchment paper.

In a medium mixing bowl, whisk together the old-fashioned oats, all-purpose flour, light brown sugar, granulated sugar, baking soda, salt, and ground cinnamon.

Pour the melted unsalted butter into the bowl with your dry ingredients. Add the eggs and vanilla extract, mixing everything until completely incorporated.

Gently fold in the semi-sweet chocolate chips using a spatula.

Spread the mixture evenly into the prepared baking pan and bake for 18 to 20 minutes.

Remove from the oven and sprinkle with sea salt. Allow to cool completely before slicing into squares.