Preheat the oven to 350 ℉. Line a baking sheet with parchment paper or a silicone baking mat.
In mixing bowl, stir flour, oats, baking powder, baking soda, cinnamon and salt. Set aside.
Using a standing mixer or a hand-held mixer with a large bowl, beat the butter on medium to medium high, about 2-3 minutes. You want it to be a pale yellow and very creamy.
Add sugar and beat another 2-3 minutes until light and fluffy, scraping down the sides of the bowl with a rubber spatula as needed.
Add the molasses and mix until fully incorporated, again scraping down the sides of the bowl as needed.
Add eggs, one at a time, allowing each egg to incorporate before adding the next. Slowly add the vanilla extract and milk and mix until incorporated. At this point the dough might look a bit watery and curdled. That’s totally fine it will firm up once you add the flour mixture.
Add the flour/oat mixture and mix on low until just incorporated. Scrape down the sides of the bowl with a spatula to make sure the dough is fully mixed and all the flour and oats have been incorporated.
Gently fold in raisins.
Using an ice cream scoop or spoon, add balls of 2-3 tablespoons of dough to prepared baking sheet, leaving around 2 inches between each cookie.
Place the baking tray in the oven and bake 10-12 minutes until the edges are golden brown.
When the cookies are done, remove from oven, let cool, and enjoy!