In a medium bowl, mix the peanut butter, butter, brown sugar, and powdered sugar together.
Melt the chocolate chips in a microwave-safe bowl for 2 minutes on 50% power (power level 5). Stir until bowl no longer feels warm, then microwave for 30 seconds more. Stir until smooth.
Place enough melted chocolate into each cavity of the mold to cover the bottom of each egg. Shape 1-2 teaspoons of the peanut butter mixture into an elongated oval disc. Gently place the peanut butter mixture onto the chocolate in each egg. Cover with more of the melted chocolate, use a spoon to gently spread it. Place the mold into the refrigerator or freezer until hardened. Store in an airtight container in the refrigerator.
If you have extra peanut butter filling and chocolate, you can layer the chocolate and peanut butter into the bottom of a muffin liner to make your own homemade peanut butter cups!
I prefer Guittard milk chocolate chips and a natural creamy peanut butter (that is still sweetened).