To begin, preheat your oven to 350 and line two pans with parchment paper (or spray with non-stick spray).
In a small mixing bowl, add your flour, baking soda, salt and cinnamon and stir them together.
In a large mixing bowl, add your butter and brown sugar and beat them together with a mixer till creamy. Add your maple syrup and vanilla and mix together again. Last, add your egg and briefly blend it into your wet ingredients.
Add your dry ingredients into your wet ingredients and stir till well combined. Add your oats and pecans and gently fold them into your cookie dough. Let your dough rest for 10 minutes for the oats to soak up the wet ingredients (or your cookies will spread too thin).
Scoop with a small cookie scoop, and space them evenly apart on your pans (with about 12 cookies per pan). Gently flatten the tops of the cookies with a spatula. Bake for 10-12 minutes, or till the tops of the cookies are set and cooked through.
Let cool, then devour!
I recommend storing these cookies in an airtight container with parchment paper in between each layer, so the cookies don't stick together. At room temperature, these cookies will last 1-2 days. In the fridge they will last about a week.