Preheat your oven to 350℉ and line two baking sheets with silicone mats or parchment paper.
Start by melting the butter. Place 1 stick of unsalted butter that's been cut into TBSP sized pieces in a microwave-safe bowl. Heat in 15-second intervals until it's fully melted, then set aside.
In a medim sized bowl, Whisk together the flour, cornstarch, baking soda, and salt. Set aside.
In a large bowl, pour in the melted and cooled butter, packed brown sugar, and granulated sugar. Using a hand mixer on low speed, mix together your ingredients until no lumps remain. The mixture should become lighter as it's whisked.
Whisk in 1 large egg and vanilla extract. Mix until the egg is fully incorporated.
Pour the dry ingredients into the butter/sugar mixture and mix together until fully combined. Scrape the bowl's sides and bottom as needed to make sure everything gets mixed together.
Mix in 1 cup of mini chocolate chips. Your mixture will be soft; that's how it's supposed to be!
Scoop the dough into a large piping bag or a freezer Ziploc bag. Cut an opening at the base of the bag that is about 1 inch in diameter. Pipe small dollops of cookie dough onto the prepared baking sheets, spacing them about 1 1/2 inches apart. (I was able to get about 40 cookies on each baking sheet)
Bake one tray of cookies at a time for 6-8 minutes. The cookies are ready when the edges just start to brown but the centers still look slightly under-baked. They will continue to bake on the sheet and firm up once removed from the oven.
Once the cookies are done baking, place the cookie sheet on a wire rack and let the cookies cool fully.