Start by preheating the oven to 350 degrees F (180C). Prepare a baking tray by lining it with a sheet of parchment paper.
Add the peanut butter, tahini, vanilla extract and plant based milk to a mixing bowl. Whisk together thoroughly to form a smooth texture.
Add the gluten-free flour, baking soda and coconut sugar. Mix using a spatula and your hands if necessary to make a dough ball. If adding dark chocolate chips, fold them into the batter.
Spoon out even dollops of the dough onto the baking tray, flattening them down slightly. Make sure to leave plenty of room between the cookies - it may be necessary to use more than one baking tray as they do spread out a lot.
Bake in the oven for around 12-15 minutes. Allow to cool for a while, and enjoy.