Heat the oven to 350°F (177°C). Non-stick cooking spray a 10-ounce ramekin and set aside.
1
Mix melted butter, brown sugar, and granulated sugar in a small bowl. Fully incorporate the egg yolk and vanilla extract.
2
Mix flour, baking soda, and salt until just combined, then gently stir in chocolate chips.
3
Press the cookie dough into the ramekin to make an even layer. Add more chocolate chips and gently press them down.
4
Bake the cookie for 20–25 minutes at 350°F until set and browned. The ramekin size determines baking time. Tent foil to prevent cookie top browning. Serve and enjoy after cooling!