In a medium bowl, whisk together the flour, baking soda, ground cinnamon, and salt until well combined.
In a separate large bowl, layer the ingredients in the jar in the following order: first, add the rolled oats evenly.
Next, add the flour mixture carefully to maintain distinct layers.
Then, add the light brown sugar evenly over the flour mixture.
Follow with the granulated sugar, spreading it evenly.
Finally, top with the semisweet chocolate chips.
Seal the jar tightly and store in a cool, dry place until ready to use.
To bake cookies, preheat oven to 350°F (175°C).
In a large bowl, combine the entire jar contents with 1/2 cup (1 stick) softened unsalted butter, 1 large egg, and 1 teaspoon vanilla extract. Mix until well combined.
Drop rounded tablespoons of dough onto an ungreased baking sheet, spacing them about 2 inches apart.
Bake for 9 to 11 minutes, or until the edges are golden brown but the centers remain soft.
Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.