Prep your pans:
Line 2 large baking sheets with parchment paper and set aside.

Combine chocolate chips:
In a medium bowl, mix 1½ cups of semi-sweet chocolate chips with 1 cup mini chocolate chips. Set aside for later—this will help give your cookies that iconic chocolate-loaded look.

Melt the butter:
In a large microwave-safe bowl, melt ½ cup unsalted butter. Let it cool to room temperature for at least 10 minutes before continuing—this is important for texture.

Mix the wet ingredients:
Once the butter is cool, whisk in 1 cup packed brown sugar until smooth. Add 1 egg and 1 teaspoon vanilla extract, stirring until completely incorporated and glossy.

Add the dry ingredients:
Stir in ½ teaspoon each of baking soda, baking powder, cornstarch, and salt. Next, add 1 cup cake flour followed by 1 cup all-purpose flour. Stir gently and avoid overmixing—the dough should just come together.

Add the chocolate chips:
Fold in 1¾ cups of the chocolate chip mixture. Reserve the rest for decorating the tops and sides of the cookies.

Shape the dough:
Use a ½ cup measuring scoop to portion out the dough into 5–6 large balls. Place them on the prepared baking sheets, spacing them 3 inches apart.

Top and flatten the cookies:
Press the remaining chocolate chips into the top and sides of each dough ball. Gently flatten each cookie to about 1½ inches thick. Avoid pressing chips into the bottom—they’ll burn while baking.

Chill the dough:
Place the baking sheets in the refrigerator for 1 hour. If your fridge can’t fit the trays, chill the dough balls on a plate first, then transfer to baking sheets.

Preheat and bake:
While the dough chills, preheat your oven to 325°F (163°C). Bake the cookies for 15–20 minutes, or until the centers are just set. For gooey Chocolate Chip Cookies, do not overbake.

Cool completely:
Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack. Enjoy warm, or let them cool completely for storage.