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 2 minutes. 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 raisins, on low speed. Dough will be thick, yet very sticky. Chill the dough for 30 minutes in the refrigerator (allow the mix to sit at room temperature for at least 30 minutes before rolling and baking).
Preheat oven to 350°F (177°C). Line baking sheet(s) with parchment paper. Set aside.
Roll balls of dough (about 2 tbsps. of dough per cookie) and place 2 inches apart on the baking sheets.
Bake for 12 to 14 minutes until lightly browned on the sides. The centers will look very soft and under-baked. Remove from the oven and let cool on baking sheet(s) 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.