Melt the dark chocolate chips in a microwave-safe bowl in short bursts until smooth.

Lightly grease heart-shaped molds with oil or nonstick spray.

Pour melted chocolate into each mold, coating the sides well, and chill for 10-15 minutes until set.

In a bowl, mix peanut butter, powdered sugar, and vanilla extract until creamy.

Fill hardened chocolate molds with the peanut butter mixture and top with more melted chocolate.

Chill for another hour until fully set, then serve at room temperature.