Preheat the oven to 375 degrees Fahrenheit and line a baking sheet with parchment paper.
In a large bowl, add in the softened butter and both sugars, beating them together using a hand mixer (or electric stand mixer)until the mixture looks smooth and fluffy. Add in the egg and vanilla, and continue to mix until combined.
In a bowl, add together the flour, oats, baking soda, baking powder, and cinnamon, whisking together until combined.
With the mixer on low-speed, add in the dry ingredients to the wet ingredients, mixing until the mixture becomes smooth, moistened, and holds together well. Fold in 3/4 the amount of chopped chocolate.
Using a medium-size scoop, scoop (about 3 Tbsps or so) each cookie dough onto the prepared baking sheet, leaving 1-2 inches between each cookie for spreading when they bake. Lightly press down on each cookie to help it spread nicely. Add the remaining 1/4 amount of chopped chocolate, pressing them in each cookie slightly----for extra fudge.
Bake for 13 to 15 minutes (checking it after about 10 minutes), or until the edges are golden brown.
Remove the cookies from the oven and cool cookies onto the baking sheet for a few minutes before transferring them unto a cooling rack to cool completely.
Enjoy with your favorite glass of dairy-free milk.