Preheat oven to 350°F. Line a baking sheet with parchment paper.
In a medium size mixing bowl, whisk together flour, baking soda, baking powder, salt, cinnamon, and nutmeg. Set dry ingredients aside.
In a large mixing bowl, using a handmixer or standmixer with paddle attachment, cream butter, brown sugar, and granulated sugar together for 3 minutes on medium speed. Use a rubber spatula to scrape down sides of bowl.
Add eggs, vanilla extract, and molasses. Mix on medium speed until just combined, around 30 seconds - 1 minute. Stop and scrape down bowl.
Add the dry ingredients to the wet ingredients then mix on low speed until just combined, around 1 minute. Stop and scrape down bowl.
Add rolled oats and raisins. Mix on low speed until just combined, around 30 seconds.
Using a cookie scoop or two spoons, scoop out 2 Tablespoons of dough for each cookie. The dough will be very sticky, so don't try to roll it. Just drop each mound of dough onto the prepared baking sheet, at least 2 inches apart.
Bake for 12-15 minutes, until edges of cookies are golden brown. The centers will still look undercooked and a little gooey. Remove from oven and let cookies cool on the baking sheet for at least 30 minutes (Yes, 30 whole minutes! Sorry!) before serving. The lengthy cooling time allows the cookies to set and become chewy instead of gooey. Removing cookies from the tray before they set will cause them to fall apart. Recipe makes around 28 cookies.