Skillet Cookie for 2

Preheat oven to 350˚F.

In a 6 ½- to 8-inch cast-iron or oven-safe stainless steel pan, melt butter over medium heat, then remove pan from heat and add in both sugars. Mix until sugars melt and mixture is smooth. Add egg yolk and mix until smooth. Add baking soda and salt, and then gradually add flour, stirring after each addition, until fully incorporated. Once the dough forms, add half of the mix-ins and then smooth the dough into an even layer. Top with the rest of the mix-ins and a sprinkle of flaky sea salt.

Bake until golden around the edges, about 10 minutes. Serve warm.