Combine softened unsalted butter, light brown sugar, and gochujang until smooth to prepare the caramel paste.

Cream together remaining unsalted butter with granulated sugar and brown sugar until light and fluffy.

Add in the egg and vanilla extract, blending until smooth.

Whisk together flour, baking soda, kosher salt, and cinnamon in another bowl.

Gradually add dry ingredients to the creamed mixture, stirring until just combined.

Cover the dough and refrigerate for 10-15 minutes.

Line baking sheets with parchment paper.

Gently fold the gochujang caramel paste into the chilled dough for a marbled effect.

Scoop dough into 12 mounds on prepared sheets, leaving space to spread.

Bake for 11-13 minutes until tops are cracked and edges are golden brown.

Cool cookies on sheets for 3 minutes before transferring to wire racks.