Combine butter with both sugars in a large bowl and beat with an electric hand mixer or do it by hand using a spatula until smooth and a bit fluffy. The mixture will look like wet sand. Beat in egg until well combined, then mix in molasses and vanilla.
In a medium bowl, combine flour, baking soda, cinnamon and salt. Add this to the butter mixture with the oats and chocolate chips and fold it in until evenly combined.
Place a piece of plastic wrap directly on the surface of the dough in the bowl and refrigerate for 1 hour.
Preheat your oven to 350°F. Line two large baking sheets with parchment paper and set aside.
Roll heaped tablespoons of dough into balls and place them on prepared baking sheets spacing them 2 inches apart. Bake for 10-12 minutes until golden around the edges and still slightly gooey in the center (they will set as they cool). Let cookies cool for 1 minute on the baking sheet and then transfer to a wire rack to cool completely.
