In a large mixing bowl, combine solid coconut oil and sugar with a hand-mixer until the sugar is fully incorporated into the oil.*
Add in the non-dairy milk and mix to combine.
Sift in the flour and mix until just combined. Use a spatula to test the texture of the dough; when pressed firmly, the dough should hold together well.**
Divide the dough into two bowls. In one bowl, mix vanilla into the dough (optional). In the second bowl, sift in cocoa powder and combine with hand-mixer. Make sure the cocoa powder is well incorporated, otherwise you'll end up with white streaks in your chocolate dough.
Transfer vanilla dough onto some plastic wrap and mould into a 3 x 3 x 9 cm cuboid. Don't worry if it isn't perfect, you can adjust the shape later on. Repeat with the chocolate dough, then let both rest in the refrigerator for 1 hour.
After 1 hour, unwrap the blocks of dough and slice each block into 9 equal strips. Then start to rearrange and layer them; white-black-white at the bottom, black-white-black in the middle and white-black-white at the top. The second dough will be the opposite, starting with black-white-black at the bottom, and so on.
Cover the two blocks of dough with plastic wrap and let rest in the refrigerator for 30 minutes.
After 30 minutes, remove the plastic wrap and gently cut the dough into 0.5 cm thin slices. Arrange neatly on a parchment-lined baking tray and bake in a preheated oven at 180°C for 15-18 minutes. Keep an eye on them because they shouldn't brown too much (like how mine turned out haha).
Let cool on baking tray for 5 minutes and transfer to a wire rack to cool. Enjoy with coffee, tea or more non-dairy milk !