Line a baking tray or brownie tin with baking paper, or a standard 12-hole muffin tin with paper cases.
In a saucepan over medium–low heat, gently stir together the melted cacao butter and coconut oil. Add the nut butter and heat, stirring frequently, for 3–4 minutes, or until the nut butter has softened and is completely incorporated into the mixture.
Remove the pan from the heat and gently whisk in the cacao power, vanilla and your sweetener of choice. Keep whisking until thick, creamy and well combined, then taste and evaluate the consistency and sweetness as follows:
For a thicker darker chocolate, add some more cacao powder.
For a smoother chocolate, add some more coconut oil.
For a fudgy chocolate, add some more nut butter.
For a sweeter chocolate, add some more sweetener of choice.
Once the chocolate is to your desired taste and consistency, pour it into your prepared tray or tin, transfer to the fridge or freezer and leave until set firm. Store in a suitable airtight container in the fridge for up to 1 month or in the freezer for up to 3 months.