Start by gathering all your ingredients and tools. Line a muffin tin with silicone muffin cups or prepare individual cups if you prefer.
In a microwave-safe bowl, add 1 pound of dark chocolate candy melts. Heat in the microwave in 30-second intervals, stirring until melted and smooth.
Spoon a small amount of melted chocolate into the bottom of each muffin cup, just enough to cover the base. Place the muffin tin in the freezer for about 10 minutes to set.
In a mixing bowl, combine the natural peanut butter with a pinch of salt, and if desired, sweeten to taste. Mix until smooth and creamy.
Spoon a generous amount of the peanut butter mixture on top of the hardened chocolate layer, filling each cup to about ¾ full.
Pour the remaining melted chocolate over the peanut butter layer in each cup, ensuring that the peanut butter is completely covered.
Before the chocolate sets, sprinkle coarse sea salt, chocolate sprinkles, or mini chocolate chips on top.
Return the muffin tin to the freezer and let the cups chill for at least 30 minutes, or until the chocolate is fully hardened.
Once set, carefully remove the Dark Chocolate Peanut Butter Cups from their molds. Store them in an airtight container.
