Prep your pan. Line a mini muffin pan with paper liners or use a silicone mold. Clear space in your fridge or freezer for quick chilling.
Melt the chocolate. In a heatproof bowl, combine chopped dark chocolate and coconut oil.
Microwave in 20–30 second bursts, stirring between each, until smooth and glossy. You can also use a double boiler.
Sweeten the chocolate (optional). If you like a sweeter shell, whisk in 1–2 tablespoons powdered erythritol or allulose while the chocolate is warm. Taste and adjust.
Make the filling. In a separate bowl, stir together peanut butter, almond flour, 2 tablespoons powdered sweetener, vanilla, and a pinch of salt.
Mix until thick and scoopable. If it’s too loose, add a teaspoon more almond flour; if too stiff, loosen with 1–2 teaspoons melted coconut oil.
Create the base layer. Spoon about 1 teaspoon melted chocolate into each muffin cup. Tilt the pan so the chocolate coats the bottom evenly.
Chill 5–10 minutes until just set.
Portion the filling. Roll the peanut butter mixture into small discs (about 1 teaspoon each) and place one on top of each chocolate base. Leave a small border around the edges for the top layer to seal.
Seal with chocolate. Spoon enough melted chocolate over each cup to cover the filling completely. Tap the pan gently on the counter to level and remove air bubbles.
Finish and chill. Sprinkle a few flakes of salt on top if you like.
Chill in the fridge for 30–45 minutes, or freeze for 15–20, until fully set.
Serve. Pop the cups out of the mold. Let them sit at room temperature for 3–5 minutes before biting for the best texture.