In a large mixing bowl, beat together the butter and brown sugar with an electric mixer until well combined, about 2 minutes.
Add the maple syrup and vanilla extract and beat to combine. Scrape down the sides of the bowl as needed.
Add the eggs, one at a time, beating until combined.
Add the flour, cinnamon, salt, and baking soda, and beat until combined, scraping down teh sides of the bowl as needed.
Add the oats and mix until well combined.
Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or overnight.
Preheat the oven to 350 degrees F.
Line 2 baking sheets with parchment paper.
Drop ~2 tablespoons of dough onto the prepared baking sheets, and bake until golden, about 14-16 minutes.
Let cool for about 5 minutes and then transfer to a wire rack to cool completely.