Weigh or measure both sugars into a bowl and set it aside. Next, weigh the flour, baking soda, baking powder, salt, cinnamon, nutmeg, and allspice into a bowl. Don't forget to use the Tare button between ingredients. I use a whisk to blend all the dry ingredients.
Using a hand or stand mixer, blend sugars and butter thoroughly for 3 to 4 minutes on a medium mixer speed. Add eggs and vanilla and incorporate. Scrape down the sides of the bowl and turn the mixer on to a slow speed.
Slowly add the dry flour mixture to the wet cookie dough. Mix for about 30 seconds. Next, scrape down the sides and add the oats and raisins. I turn the mixer on for about 10 to 15 seconds. If you need to mix a little more, or you can use a spatula to ensure they are evenly distributed. Because of the butter, I stick the dough on the refrigerator for 20-30 minutes.
Preheat oven to 350°F (175°C or 180°C). Line 2 cookie sheet pans with parchment paper. I am using a medium cookie scooper to place twelve mounds onto each cookie sheet pan. Bake for 12-14 minutes. The edges should just be a little brown. If you overbake the cookies they can become hard in a few days.
Once you pull them out of the oven, the tops will be soft but firm up after they are out of the oven. Leave on the pan for a minute or two. Then move the cookies to a cooling rack to finish.