Step 1: In a large mixing bowl, combine the softened unsalted butter, creamy peanut butter, and vanilla extract. Beat with an electric mixer on medium speed until the mixture is smooth and well combined.
Step 2: Gradually add the powdered sugar to the peanut butter mixture, one cup at a time, beating on low speed until fully incorporated. The mixture will become very thick and crumbly. Once all the sugar is added, increase the speed to medium-high and beat until the mixture comes together into a firm, pliable dough. If it's too sticky, add a little more powdered sugar; if too dry, add a tiny bit more melted butter or peanut butter.
Step 3: Roll the peanut butter mixture into egg shapes, about 1 to 1.5 inches long. Place the formed peanut butter eggs onto a parchment-lined baking sheet.
Step 4: Chill the peanut butter eggs in the refrigerator for at least 30 minutes, or in the freezer for 15-20 minutes. This step is crucial for easy dipping.
Step 5: While the eggs are chilling, prepare your chocolate coating. In a double boiler or a microwave-safe bowl, melt the chocolate chips with the shortening (or coconut oil) over low heat, stirring frequently until smooth. If using a microwave, heat in 30-second intervals, stirring after each, until melted and smooth.
Step 6: Remove the chilled peanut butter eggs from the refrigerator or freezer. Using a fork or a dipping tool, carefully dip each peanut butter egg into the melted chocolate, allowing any excess chocolate to drip off. Gently place the coated peanut butter eggs back onto the parchment-lined baking sheet.
Step 7: If desired, immediately after dipping, sprinkle the tops of the chocolate-covered peanut butter eggs with flaky sea salt or other decorations.
Step 8: Return the chocolate-coated peanut butter eggs to the refrigerator for another 15-30 minutes, or until the chocolate has fully set. Once set, they are ready to serve and enjoy! Store any leftover peanut butter eggs in an airtight container in the refrigerator.