In a large bowl, combine softened coconut oil with brown sugar.
¼ cup (54 g) coconut oil, ½ cup (100 g) dark brown sugar
Mix with a spatula or spoon until soft and well combined.
Add the vanilla extract and stir in.
1 teaspoon vanilla extract
Add the flour, baking powder and salt and stir until roughly combined.
¾ cup + 2 tablespoons (105 g) all-purpose flour, ½ teaspoon baking powder, ¼ teaspoon coarse salt
Stir in just enough cold water until the mixture comes together into a smooth dough.
1 to 2 tablespoons water
Mix in the finely chopped walnuts until evenly incorporated.
1 cup (100 g) walnuts
Transfer the dough onto a work surface and form it into a log shape 1 ½ inches / 4 cm thick. A square-shaped log makes the cookies easier to slice.
Wrap in plastic wrap and chill in the fridge for at least 1 hour.
Preheat oven to 325°F / 160°C. Line a large baking sheet with parchment paper or a reusable baking mat.
Slice the chilled log of dough into ¼ inch / 6mm thick cookies using a sharp knife.
Place cookies on the baking sheet, leaving a space of at least ¾ inch or 2 cm between them.
Bake for 18-20 minutes until they are golden brown and just firm to the touch.
Cool on the baking sheet for 5 minutes and then transfer to a cooling rack.