Step 1: Prepare the Hazelnut Filling

1. Toast Hazelnuts: If using raw hazelnuts, toast them in a preheated oven at 350°F (175°C) for about 10-12 minutes until golden and fragrant. Let them cool.
2. Mix Filling: In a bowl, combine the chopped hazelnuts, Nutella, and powdered sugar (if desired). Mix until well combined.
3. Form Balls: Roll the mixture into small balls (about 1 inch in diameter) and place them on a parchment-lined baking sheet. Freeze for about 30 minutes to firm up.

Step 2: Prepare the Wafer Shell

1. Melt Chocolate: Melt 1 cup of milk chocolate in a microwave-safe bowl or over a double boiler until smooth.
2. Coat Wafers: Dip each wafer cookie halfway into the melted chocolate, allowing the excess to drip off. Place them on a parchment-lined baking sheet to set.

Step 3: Assemble the Ferrero Rocher

1. Wrap Filling: Take the chilled hazelnut balls from the freezer. Place one hazelnut ball on top of each chocolate-coated wafer. Gently press down to secure.
2. Coat Again: Dip the entire wafer and hazelnut ball into the melted chocolate, ensuring it is fully coated. Allow excess chocolate to drip off.
3. Roll in Hazelnuts: Immediately roll the coated Ferrero Rocher in the chopped hazelnuts to cover completely.

Step 4: Chill and Serve

1. Chill: Place the finished Ferrero Rocher back on the parchment-lined baking sheet and refrigerate for at least 30 minutes to set.
2. Serve: Once set, serve and enjoy your homemade Ferrero Rocher!