Soak the cashews in hot water to soften. This takes about 30 minutes. During that time I like to start working on the pastry dough.
Once the cashews are soft, add them to a blender together with the nutritional yeast, salt and oat milk and blend until smooth (ish) - it's ok if there's still some chunks of cashews left after blending, it doesn't have to be a paste.
Add the frozen spinach to a pot and heat it up until defrosted and warm.
To a bowl, add the cashew creme and cooked spinach.
Finely dice the red onion and cut the sundried tomatoes into small pieces. Add them to the bowl too and mix everything until combined.
Add flour, salt and oregano to a big bowl. Mix until combined.
Now add the olive oil and water and lightly kneed the dough until smooth. It won't be a super elastic dough, just make sure its combined. Wrap the dough in glad wrap and place in the fridge to rest for 30minutes (don't rest the dough for much longer than that as the oil will freeze and the dough gets hard to roll out).
Once the dough has rested, take it out of the fridge and roll it out onto a lightly floured surface.
How to bring it together
Preheat the oven to 180°C and coat the muffin tray lightly in olive oil as well as lining it with small baking paper strips to ensure the tartlets can easily be removed after baking.
Cut big round circles out of the pastry with either a cookie cutter or use a bowl as a template. Put the pastry into the muffin holes.
Spoon the filling, about 1 tablespoon into each pastry dish.
Bake the tartlets for about 20 minutes. Once baked, let them cool down for just a few minutes and enjoy warm.