Pre-heat your oven to 180°C/ 356°F. Line the bottom of your baking tray with baking paper and grease the sides with some butter. Note, I used a small 15cm baking tray with a removable bottom for this recipe. If your baking tray is bigger, bear in mind that your brownies will be thinner than mine photographed. To combat this, you could increase the ingredient amounts.
In a saucepan, melt your butter on a low heat. Once melted, add your milk, sugar and vanilla extract and combine. Then add the chocolate. Take off the heat and continue stirring until the chocolate is completely melted.
In a large bowl, sieve the flour, cocoa powder and salt. Combine together with a spoon.
Pour the wet ingredients into the large bowl with the dry ingredients. Mix together.
Add 25g of hazelnuts to the brownies mixture and combine until fully incorporated.
Pour your brownie mixture into your lined baking tray. Then, add your ferrero rochers on top, pushing them into the batter. I added six whole ferrero rochers and 2 halved. You can choose however you want your brownies to look here! Then, scatter the remaining hazelnuts on top.
Bake your brownies for 25 minutes.
Once the time is up, remove the brownies from the oven. They should have developed a crackly top but will still be lovely and gooey in the middle. Leave the brownies to completely cool.
Cut them up and devour! I hope you love them.