Using a mixer, 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. 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, raisins, and walnuts (if using) on low speed. Chill the dough for 30-60 minutes.

Preheat oven to 350°F (177°C). Line baking sheets with parchment paper. Roll balls of dough and place on the baking sheets. Bake for 12-14 minutes until lightly browned. Let cool on the baking sheet for 5 minutes before transferring to a wire rack.