Using a hand mixer or a stand mixer fitted with paddle attachment, cream the softened butter and both sugars together on medium speed until smooth, about 3 minutes. (Here’s a helpful tutorial if you need guidance on how to cream butter and sugar.) Add the eggs and mix on high until combined, about 1 minute. Scrape down the sides and bottom of the bowl as needed. Add the vanilla and molasses and mix on high until combined. Set aside.

In a separate bowl, whisk the flour, baking soda, cinnamon, and salt together. Add to the wet ingredients and mix on low until combined. Beat in the oats and chocolate on low speed. Dough will be thick, yet very sticky. Chill the dough for 30-60 minutes in the refrigerator (I always chill this dough for only 30 minutes). If chilling for longer (up to 2 days), allow to sit at room temperature for at least 30 minutes before rolling and baking. The cookies won’t spread as much if chilled for longer than 1 hour.

Preheat oven to 350°F (177°C). Line two large baking sheets with parchment paper or silicone baking mats. Set aside.

Roll balls of dough (about 1 and 1/2 Tablespoons of dough per cookie) and place 2 inches apart on the baking sheets. I recommend using a cookie scoop since the dough can be sticky. Bake for 11-12 minutes or until lightly browned on the sides. The centers will look soft and under-baked. Remove from the oven, immediately sprinkle each with sea salt (if using), then let cool on baking sheet for 5 minutes before transferring to a wire rack to cool completely. The cookies will continue to “set” on the baking sheet during this time.

Cover and store leftover cookies at room temperature for up to 1 week.