Line a muffin tin with paper liners or silicone molds to prepare for pouring.
Gently melt the chocolate using a double boiler or microwave, heating in short bursts and stirring until smooth and glossy. This should take about 2 minutes in the microwave or a few minutes over gentle heat.
Spoon a small amount of melted chocolate into each mold, just enough to cover the bottom. Tap the tray gently on the counter to level the chocolate and remove air bubbles.
Place the mold in the fridge for about 5 minutes until the chocolate is just set but not completely hard.
Mix the peanut butter with honey or maple syrup, sea salt, and vanilla until smooth and creamy. Slightly warming the peanut butter makes it easier to spread.
Drop a teaspoon of peanut butter on top of the chilled chocolate layer, then gently press it down to spread evenly without breaking the chocolate.
Cover the peanut butter with more melted chocolate, smoothing the surface with a spatula or the back of a spoon to seal the filling.
Chill the assembled cups in the fridge for at least 30 minutes until fully firm and glossy.
Carefully remove the peanut butter cups from the molds, gently peeling away the liners or silicone.
Store the peanut butter cups in an airtight container in the fridge for up to 2 weeks, or keep them in the freezer for longer storage.
Enjoy directly from the fridge for a firm bite, or let them sit at room temperature for a few minutes for a softer, melt-in-your-mouth experience.