Preheat the oven to 350°Fahrenheit/175°Celsius. Line a baking sheet with parchment paper.
In a stand mixer fitted with the paddle attachment, or in a large bowl with a handheld mixer, beat the butter for 2-3 minutes until creamy and soft. Add the light brown sugar and white sugar and beat for another 2 minutes.
½ cup unsalted butter, ½ cup light brown sugar, 2 tablespoons white sugar
Scrape down the sides of the bowl with a rubber spatula. Add the egg yolk, vanilla extract and molasses and mix once more.
1 large egg yolk, 1 teaspoon vanilla extract, ½ tablespoon unsulphured molasses
Pour in all of the dry ingredients - flour, oats, baking soda, salt, cinnamon, nutmeg and cornstarch. Mix on low until just combined, then stop the mixer.
½ cup all purpose flour, ½ teaspoon ground cinnamon, pinch ground nutmeg, ¼ teaspoon kosher salt, ½ teaspoon baking soda, 1 ½ cups old fashioned oats, pinch cornstarch
Stir in the chocolate chips. Use a large cookie scoop or a tablespoon to scoop out 3 tablespoons of dough. Roll into a ball. Optional, add more chocolate chips on top of each cookie dough ball!
½ cup chocolate chips
Place the cookie dough balls on the baking sheet, making sure they're 2-3 inches apart. Bake for 13-14 minutes. The edges will be set but the middle will be slightly underbaked. Let them cool for 15 minutes on the baking sheet then remove to a wire cooling rack to cool completely.
Notes
My recipes have been developed and tested in metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way. Butter: I use European style butter, like Kerry Gold, in my recipes. This will make your finished bake much creamier and richer.Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt. Please note I am using Diamond Crystal Kosher Salt and not Morton Salt, which is a coarse kosher salt. Coarse kosher salt is much too salty for this recipe. Storage: keep the baked cookies in a tupperware for up to 1 week at room temperature. Freeze unbaked cookie dough balls for up to 2 months. When ready to bake, take them out of the freezer and bake at the same temperature as above but for an extra minute or two.