Set up a double boiler by filling a small saucepan with a few inches of water and bringing it to a gentle simmer. Place a heatproof mixing bowl on top, ensuring it doesn’t touch the water.
Add chopped dark chocolate into the bowl and slowly melt, stirring frequently with a silicone spatula. Keep an eye on the texture until the chocolate is smooth and glossy, about 5-7 minutes.
In a separate bowl, combine peanut butter, melted butter, powdered sugar, and vanilla extract. Mix vigorously until the mixture is smooth, creamy, and slightly fluffy.
Pour the melted chocolate into the peanut butter mixture and fold together until fully incorporated and shiny. The mixture should be thick but still pourable.
Use a mini scoop or teaspoon to portion out small balls onto a baking sheet lined with parchment paper. Place the sheet in the fridge and chill for about 30 minutes until the truffles are firm.
Once chilled and set, dip each truffle into the remaining melted chocolate, or roll in toppings if desired. Place back on the parchment-lined sheet, and sprinkle with sea salt flakes on top for added flavor.
Let the coated truffles sit at room temperature for about 10 minutes until the chocolate firms up completely. Then, they are ready to serve and enjoy!