Preheat the oven to Fan 170°C / 190°C/375°F/Gas 5. Line two baking sheets with parchment paper.
Prepare the chia egg by mixing 1 Tbsp of ground chia seeds with 3 Tbsp of water. Set aside for 10 mins.
Sift sugars and mix together with butter until you have a creamy texture.
Add sifted flour and salt into the bowl. Mix in chia egg, vanilla extract and almond milk. Fold in chocolate chips with a wooden spoon.
Take one scant tablespoon of cookie dough and place on baking sheet. Shape and flatten to a 5cm / 2 inches diameter circle. Repeat with the rest of the cookie dough, making sure you space the cookies apart as they will become bigger when cooking.
Bake for 10–12 mins. The cookies should be light brown and slightly soft in the centre when pressed. When done, remove from the oven and leave on baking trays for 10 mins. When the cookies are cold enough to be moved, transfer them carefully to a cooling rack and leave to cool down completely.