In a double boiler or a heatproof bowl set over simmering water, melt the coconut oil or cocoa butter. Ensure the water doesn't touch the bottom of your bowl.
Once the oil or butter is melted, whisk in the unsweetened cocoa powder until smooth.
Stir in the powdered erythritol, ensuring it's fully dissolved and the mixture is smooth. Adjust sweetness to taste.
Add the vanilla extract and a pinch of sea salt, mixing well.
Pour the chocolate mixture into silicone molds, chocolate bar molds, or a parchment-lined tray if you prefer a bark format.
Place the molds or tray in the refrigerator for at least 2 hours or until the chocolate is solid.
Once set, remove the chocolate from the molds or break the bark into pieces. Store in a cool place or the refrigerator, especially if using coconut oil, as it tends to melt at warmer temperatures.