Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4 and grease and line a 12" x 9" tin
Melt the dark chocolate and butter together in a pan on a low heat. When fully melted, stir together and remove from the heat. Let it cool for 10 minutes
In a mixing bowl use an electric mixer to whisk together the eggs, light brown sugar and vanilla extract for 5 minutes until thicker and paler in colour
Add the chocolate mixture to the egg mixture, whisking constantly as you pour it in
Add the plain flour and whisk in gently with a hand whisk until you can't see any more flour
Gently mix the chopped Kinder chocolate and Kinder Bueno bars into the brownie batter
Pour the batter into your lined tin. Add spoonfuls of the Nutella spread all over the brownie batter, then use a butter knife to swirl it into the batter
Bake for 20 minutes, or until a cocktail stick poked into the centre comes out with moist crumbs on it, but is not wet
Let the brownies cool completely in the tin before removing and slicing up
Store in an airtight container in a cool place and eat within 3 days
Video
Notes
Make sure your eggs are at room temperature before you start baking. The butter can be cold for this recipe, as you are going to melt it anyway. It will just take slightly longer to melt.
I used unsalted butter for this recipe.
I used light brown soft sugar for the brownies, which I do recommend using as it makes them extra fudgey, but you can also use caster sugar.
If you like, you could also stir some chopped hazelnuts into the brownie batter
For all of the answers to more questions about brownies, check out my Chocolate Brownies guide!
Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50) .
For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.
If you would like to use a 8" or 9" square tin, you can use the same amount of ingredients, the difference will be the thickness of the brownies and the baking time. If you are using an 8″ square tin, I recommend a baking time of 35-40 minutes. For a 9″ square tin I recommend 25-30 minutes.