Preheat a toaster oven to 350°.
In a small microwave-safe bowl, heat the butter until just softened, about 10 seconds.
Using a fork, blend in both sugars, the vanilla and a pinch of salt.
Blend in the flour, then stir in the chocolate chunks.
Scoop the batter onto a parchment paper–lined toaster tray and sprinkle with salt.
Bake for 13 to 15 minutes, until lightly browned.
Let cool slightly before serving.
