Preheat oven to 180 degrees celsius. Grease and line a 20cm square baking tin with baking paper and set aside.
Place the butter and chocolate into the Thermomix bowl. Melt for 3-4 minutes, 50 degrees, Speed 2. Allow to cool slightly.
Add the eggs, sugar and vanilla extract and mix for 10 seconds, Speed 4.
Add the flour and salt and mix for 10 seconds, Speed 4. Scrape down the sides of the bowl and mix for a further 5 seconds. Pour into the prepared tin.
Slice the Cadbury Creme Eggs in half lengthways (I found a serrated knife was the best tool for this job) and arrange them on the top of your brownies.
Press them into the brownie batter as they will sink whilst baking.
Bake for 30 minutes. When the brownie is ready the top should be dried to a pale brown but the middle still dark and slightly gooey.
Once the brownies are cooled, slice into small pieces.