2cupschocolate chipsI prefer semisweet or dark, but milk or even white chocolate chips would work, depending on your preference
Place butter in large bowl and beat with an electric mixer (alternatively you can use a stand mixer) until creamy.
Add brown sugar and granulated sugar and beat until thoroughly combined.
Add eggs, vanilla extract, and maple syrup and stir until well-combined.
In a separate, medium-sized bowl, whisk together flour, cornstarch, baking soda, salt, and cinnamon.
With mixer on low speed, gradually add flour mixture to the butter mixture until ingredients are completely combined.
Add oats and chocolate chips, stirring until thoroughly combined.
Cover bowl with plastic wrap and transfer cookie dough to refrigerator. Chill for at least 30 minutes¹.
Preheat oven to 350F (175C) and prepare cookie sheets by lining with parchment paper.
Once dough has chilled, drop cookie dough by rounded 2 Tablespoon-sized scoops onto parchment paper, spacing cookies at least 2" apart.
Bake on 350F (175C) for 12-13 minutes (edges should be slightly browned, centers may still be slightly underbaked but shouldn't be raw, they'll bake completely as they cool).
Allow cookies to cool completely on cookie sheet before enjoying.
¹Dough may be chilled longer, up to several days, just keep in mind that if it sits longer than several hours it will be very firm and difficult to scoop and may need to sit at room temperature for 15 minutes or so to soften enough to scoop.