Cream Butter & Sugar: Put the softened butter and 1 cup of the powdered sugar in a large bowl. Mix on medium speed until the mixture is light and fluffy.
Add Fillings: Add the peanut butter, marshmallow fluff, vanilla extract, and chopped peanuts (if using). Mix on medium speed until well-blended.
Adjust Texture: Gradually add the remaining powdered sugar, 1/2 cup at a time. Mix until the candy reaches a workable texture—it should be firm enough to handle but not dry. If it is still too sticky, add a little more powdered sugar.
Shape: Roll a small amount of the mixture in your hands and flatten/taper it until it resembles an egg shape.
Chill: Place shaped eggs on a baking sheet lined with aluminum foil or parchment paper. Put the tray in the refrigerator for at least one hour to firm up.
Melt Chocolate: Place the candy coating in a microwave-safe bowl. Microwave in one-minute increments, stirring after every minute, until smooth and melted.
Dip: Dip the cold eggs into the chocolate coating. Lift out with a fork, tap to remove excess, and return to the lined sheet.
Decorate: While wet, you can sprinkle with chopped peanuts or sprinkles. Alternatively, let them set and then drizzle with extra chocolate (as shown in photos).
Store: Refrigerate for 30 minutes to set the coating completely. Store in an airtight container in the fridge.