Preheat the oven to 350°F (175°C)
Line baking sheets with parchment paper
Cream together 1 cup softened butter, 1 cup brown sugar, and 1/2 cup granulated sugar
Beat in 2 large eggs and 1 teaspoon vanilla extract
In a separate bowl, whisk together 1 1/2 cups all-purpose flour, 1 teaspoon baking soda, 1 teaspoon ground cinnamon, and 1/2 teaspoon salt
Stir the dry ingredients into the wet ingredients
Mix in 3 cups old-fashioned oats and 1 cup raisins
Scoop tablespoon-sized portions of dough onto the prepared baking sheets
Bake for 10 to 12 minutes until the edges are lightly golden
Cool on the baking sheet for 5 minutes
Transfer to a wire rack to cool completely