Mix the peanut butter, honey, protein powder, and vanilla extract in a bowl until smooth.
Melt the dark chocolate chips and coconut oil (if using) in a microwave-safe bowl.
Lining a muffin tin with cupcake liners or lightly greasing it, pour a layer of melted chocolate into each cup.
Chill the chocolate layer in the refrigerator for about 10 minutes until it firms up.
Spoon the peanut butter mixture over the set chocolate layer in each cup.
Cover the peanut butter layer with another layer of melted chocolate.
Chill the filled cups in the refrigerator for at least 30 minutes until fully set.
Remove the cups from the muffin tin and enjoy!