Preheat the oven to 160°C and line a 12-hole muffin tray with silicone or paper liners.
For the biscuit base, mix together all the ingredients in a bowl. Divide the mixture evenly among the muffin holes, then use your fingers to press it down to create an even flat layer. Transfer to the oven and bake for 12–15 minutes, or until set and slightly coming away from the edges. Remove from the oven and leave to cool completely.
For the mint filling, melt the coconut oil and coconut butter in a saucepan over medium–low heat, stirring until well incorporated. Remove from the heat and stir in the peppermint oil and stevia or monk fruit syrup.
Set aside to cool slightly then spoon the mixture evenly over the biscuit layer in the muffin holes, using about 1 tablespoon per hole. Transfer to the freezer for the mint layer to set completely, about 30 minutes.
For the chocolate topping, melt the chocolate in a small saucepan over low heat, stirring, until thick and creamy. Remove from the heat and leave to cool slightly so that it is still runny but not super-hot.
Once the mint filling is set, remove the tray from the freezer and pour the melted chocolate evenly over the top to cover completely. Return to the freezer for another 30 minutes or until the chocolate topping has set completely.
When ready to serve, remove the slices from the tray and leave to soften and come to room temperature. Enjoy.