Note: As this is a small batch recipe, please ensure you measure your ingredients accurately. For the best results, use the grams measurements where provided. If using measuring cups, use the spoon and level method where you fluff up the flour in your container with a fork, use a spoon to add it to your measuring cup and level it off with a knife. Using too little or too much of any ingredient makes a huge difference in a small-batch recipe.
Preheat oven to 180°C (350°F). Line a small baking tray with parchment paper.
Add the sugar, cooled butter, milk and vanilla to a small mixing bowl. Mix with a spatula or spoon until smooth.
Add the flour and baking soda and mix until there are no pockets of dry ingredients. Add the chocolate and mix until just combined. The cookie dough should be soft and tacky.
If making one cookie, shape the dough into a large ball and place it in the middle of your cookie sheet. If making two cookies, divide the dough into 2 balls and arrange on your baking sheet with space between them. The cookies will spread a lot in the oven. If desired, press extra chocolate chips onto the cookie dough ball(s).
Bake one large cookie for 15-17 minutes, or bake two smaller cookies for around 11 minutes. The cookie(s) are ready when they're evenly golden brown, the edges look set and the center is still soft. When you take the cookie(s) out of the oven, they will continue baking.
Let the cookie(s) cool on the baking sheet for 15 minutes then transfer to a wire rack. Enjoy warm or at room temperature! If you have any leftovers, keep it in an airtight container at room temperature for up to 3 days.