In a medium bowl, whisk together the flour, cinnamon, and baking soda; set aside.
Combine the butter with both sugars; beat on medium speed until light and fluffy.
Reduce speed to low; add the salt, vanilla, and eggs. Beat until well mixed, about 1 minute.
Add flour mixture; mix until almost combined.
Stir in the oats, and raisings. Cover and chill dough for one hour to overnight.
Preheat oven to 375 degrees.
Use a cookie scoop (two tablespoons) to drop balls of dough about 2 inches apart on baking sheets lined with parchment paper.
Bake until cookies are golden around the edges, but still soft in the center, 8 to 10 minutes.
Remove from oven, and let cool on baking sheet 1 to 2 minutes. Transfer to a wire rack, and let cool completely.
Notes
Measure your flour correctly! Adding too much flour can really affect the taste and texture of the cookies. The easiest way to measure flour is by using a scale to ensure accurate results every time. If you don’t have one then fluff your flour with a spoon, spoon it into your measuring cup, and use a knife to level it off.
Make sure your butter is just at room temperature and not melted or it'll affect the shape of your cookies.
To make your raisins extra juicy you can soak them in warm water for 10 minutes then pat dry before mixing them into the batter. This helps to plump them up but is an optional step.
Chilling the dough is optional but it makes a cookie that spreads out less, concentrates the flavor, and dehydrates the dough a bit as well. I recommend chilling the dough for a minimum of 1 hour.
After chilling if the dough is too hard to scoop leave it on the counter for around 10 minutes to soften slightly.
Make sure to line your baking sheet with parchment paper or a silicone mat so your cookies don't stick.
Toasted walnuts or pecans make an excellent addition to this cookie. Try adding in 1/2 to 1 cup of chopped nuts.
Instead of nuts, you can add 1/2 to 1 cup chocolate chips or chunks.
1/2 tsp of ground cinnamon gives the oatmeal raisin cookies just a hint of it but you can add 1 tsp for a more prominent flavor.
Place the cookies about 2 inches apart on the baking sheet so they have enough room to spread.
Your cookies are done when the edges start to brown. The centers will not be raw but they won't fully set until they cool.
Storage - raw cookie dough will keep in the fridge for up to 2 days or can be frozen for 2 months. Baked cookies will keep well in an airtight container for up to 2 weeks or can be frozen for up to 2 months.