Combine the walnuts, dates, oats and salt in a high-quality food processor, and process unti small crumbles form and the dough begins to stick together in one big ball.
If mixture is too dry, add up to 2 tablespoons water and continue to process.
Break off pieces of dough with your hands and press inside one 24 cup or two 12-cup mini muffin tins, presseing down in the middle so that a cup shape is formed. Freeze for 20 minutes, until hardened.
Cashew Cream
In a food processor or blender, process the drained cashews, dates, vanilla, water and salt until completely smooth, scraping down the sides occasionally. Add more water if it seems too thick.
Pop the frozen tart shells out of the tin and fill with the cream. Refrigerate until ready to serve. Top with berries and enjoy!