In medium saucepan, combine the peanut butter, butter, and brown sugar over medium heat. Heat until completely melted and starting to bubble a little, stirring constantly. Remove from heat. Add the powdered sugar 1/4 cup at a time, stirring after each addition until completely combined. Set aside and let cool to room temp.
Melt chocolate chips and shortening in the microwave at 30 second increments, stirring after each, until fully melted. Using a small spatula, drizzle chocolate into the compartments of the egg shaped silicone mold, being careful to coat the bottom and sides. Refrigerate until hardened.
Pull chocolate molds out of the fridge and roll peanut butter mixture between hands to create an oval shape. Press into the molds making sure it is flattened and there is space along the side and top of the mold to coat with chocolate.
Drizzle remaining chocolate over the molds and coat completely. Let harden for an hour in the fridge before serving, and store in the fridge for up to a week.