To the bowl of a stand mixer fitted with the paddle attachment, add the butter, egg, brown sugar, vanilla, and beat on medium-high speed to cream ingredients until very light and fluffy, 4 to 5 minutes. Stop, scrape down the sides of the bowl, and add the oats, cinnamon (I use 1 tablespoon), baking soda, optional salt, and beat to incorporate, about 1 minute. Add the flour and beat to just incorporate, about 30 seconds. Note regarding flour - the secret to these cookies staying thick and chewy is the bread flour; although all-purpose may be substituted, the results will be superior with bread flour. Add the raisins and beat momentarily to incorporate. Transfer mixture to an airtight container or cover mixing bowl with plasticwrap and refrigerate dough for at least two hours, up to 5 days. Do not bake these cookies with dough that has not been properly chilled because they will spread. Preheat oven to 350F, line a baking sheet with a Silpat Non-Stick Baking Mat, parchment, or spray with cooking spray; set aside. Using a medium-sized two-inch cookie scoop form dough mounds, which is approximately two heaping tablespoons, or 1.50 to 1.60 ounces by weight. Place dough on baking sheet, spaced at least 2 inches apart (maximum of 8 per sheet). Bake for 10 to 12 minutes, or until edges are set and tops have just set, even if slightly undercooked in the center, as cookies will firm up as they cool. Its a little tricky to judge doneness because of all the oats, but I suggest the lower end of the baking range and baking for 10 minutes for soft and chewy cookies. For crunchier cookies, extend baking time by 1 to 2 minutes, but take care not to overbake or they will be hard. Allow cookies to cool on the baking sheet for 5 minutes before removing. Store cookies in an airtight container at room temperature for up to 5 days, or in the freezer for up to 3 months. Alternatively, unbaked dough can be stored in an airtight container in the refrigerator for up to 5 days, or in the freezer for up to 3 months, so consider baking only as many cookies as desired and save the remaining dough to be baked in the future when desired.