Start by preheating your oven to 350°F (175°C). Properly preheating ensures that your cookies bake evenly. Trust me, this step is vital!

In a mixing bowl, combine the butter, dark brown sugar, and granulated sugar. With an electric mixer, beat them together until the mixture becomes creamy. Next, add in the eggs and vanilla extract. Continue mixing until everything is well blended.

In another bowl, whisk together the flour, cornstarch, baking soda, sea salt, and ground cinnamon. The cornstarch is a secret weapon that will help keep your cookies soft. After mixing, gradually add these dry ingredients to the wet mixture, stirring until combined.

Once your dough is prepared, gently fold in the chocolate chips and chopped nuts (if you're using them). Ensure they are evenly distributed throughout the dough, creating pockets of joy in every bite.

Using a cookie scoop or two tablespoons, portion out the dough onto a baking sheet lined with parchment paper. Make sure to leave enough space between each cookie to allow for spreading during baking. Bake them in the preheated oven for about 10-12 minutes, or until the edges are golden brown.

Once baked, remove the cookies from the oven and let them cool on the baking sheet for 5 minutes before transferring them to a wire rack. This cooling process allows them to firm up, ensuring a nice texture for your treats.