Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a large mixing bowl, combine the tahini, brown sugar, and white sugar. Mix until well blended.
Add in the egg and vanilla extract, whisking until fully incorporated.
In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Fold in the dark chocolate chunks and chopped nuts (if using) with a spatula, ensuring an even distribution.
Scoop tablespoon-sized balls of dough onto the prepared baking sheet, leaving space between each cookie.
Bake in the preheated oven for 10-12 minutes, or until the edges are golden brown and the centers look slightly underbaked.
Remove from the oven and let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.
Notes
Serve warm, optionally dusted with sea salt or alongside vanilla ice cream.