In a medium saucepan, combine ½ cup of unsalted butter, ½ cup of light brown sugar, and 3 tablespoons of gochujang over low heat. Stir continuously until the mixture becomes smooth and slightly thickened, about 3-5 minutes. Remove from heat and allow to cool slightly.

In a large mixing bowl, cream together ½ cup of unsalted butter with ½ cup of granulated sugar and ½ cup of light brown sugar using an electric mixer on medium speed until light and fluffy, approximately 2-3 minutes. Add one large egg and 1 teaspoon of vanilla extract, mixing well until fully incorporated.

In a separate bowl, whisk together 1 ½ cups of all-purpose flour, 1 teaspoon of baking soda, ½ teaspoon of kosher salt, and ½ teaspoon of ground cinnamon (if using). Gradually add the dry ingredients to the butter-sugar mixture while mixing on low speed until no dry flour remains.

Cover the cookie dough tightly with plastic wrap and refrigerate for 10 to 15 minutes. Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

Remove the cookie dough from the refrigerator and gently fold in dollops of the gochujang caramel paste to create a marbled effect.

Using a cookie scoop or tablespoon, portion the dough into 12 mounds and place them evenly spaced on the prepared baking sheets. Optionally, sprinkle flaky sea salt on top.

Bake for 11 to 13 minutes, or until the tops appear cracked and the edges are golden. The centers should remain soft and chewy.

Allow to cool on the sheets for 3 minutes before transferring to a wire rack to cool completely.