Preheat oven to 350 F.
Place the butter and sugar in a bowl or standing mixer and beat for 3-5 minutes on medium high or until light and fluffy.
Add the egg and vanilla extract and beat for another minute on medium speed or until completely combined.
In a separate bowl, mix to combine the flour, oats, baking soda, salt, and cinnamon.
Slowly add the dry ingredients into the wet and mix to incorporate.
Stir in the raisins. Using a 1 tbsp mini ice cream scooper or spoon, place on a silpat or parchment-lined cookie sheet.
Bake for 12-14 minutes for chewier cookies or 15-17 minutes for more crisp cookies.
Cool on baking sheet.