Preheat the oven to 180oC/Gas Mark 4 and line 6 mini tartlet tins with greaseproof paper, or grease with vegan butter.
In a mixing bowl, combine the flour, coconut oil, maple syrup and pistachios. Mix and bring together with your hands until a dough forms.
Press the dough into the lined tins, prick the base with a fork, then bake for 9-10 minutes, until golden in colour. Allow to cool fully before filling.
Peel and de-stone an avocado and place into a bowl.
Add the melted chocolate and cacao powder and mix until combined and smooth.
Spoon some of the chocolate filling into each tart and level with a spoon or spatula.
Swirl some peanut butter into the chocolate filling if desired.
Drain the chickpea brine from a tin of chickpeas and place into a mixing bowl. Whizz up on high until foamy, then add the cream of tartar. Add the sugar and continue to whip until stiff meringue peaks form.
When thick and glossy, add the vanilla.
Place the meringue in a piping bag fitted with a patisserie nozzle and pipe a swirl of meringue onto each tartlet. You can toast the meringue either using a blow torch or by popping under the grill for a few seconds.