Preheat the oven to 175°C/350°F.
Using melted coconut oil, grease six 4-inch tart tins (you can find these in kitchen stores).
Mix the oat flour, ground almonds, coconut oil, coconut sugar, cinnamon, ginger and vanilla in a large mixing bowl until the mixture resembles breadcrumbs.
Add in 1-2 tbsp water and mix to a dough.
Divide the mixture between your tins, pressing it into the sides and bottom of the tin (you want to create a shell to hold your tart filling, so ensure there is a hollow space for the mixture).
Bake for 15 minutes, until bases are golden.
When you remove them from the oven, you may notice that the tart bases have risen quite a lot – this is normal. Using the bottom of a dessert spoon, gently push the bases back down to ensure you maintain a hollow for the filling to go in.
After 10 minutes turn each base out onto a wire rack to cool.