Cut brioche into 1 1/2 inch cubes and place in a large bowl and set aside.
Whisk together egg and yolks.
While still whisking slowly add half and half and then 3 tbsp of butter to create a custard.
Add sugar, vanilla and cinnamon and then whisk to combine.
Pour 2/3 of custard over the brioche cubes and allow the bread to absorb the custard.
Once custard has been absorbed, place a layer of the soaked bread in a baking dish, measuring approx. 9 x 9 x 5.
Mix strawberries and raspberries together then scatter 3/4 on top of the bread.
Apply another layer of bread and push down gently so that bread doesn't sit above the top of the baking dish.
Scatter the rest of the berries on top. This layer of berries should be sparse with edges of bread sticking out throughout.
Brush the top with 2 tbsp of butter then place in a preheated oven at 350 for 25-30 mins.
Serve warm with sauce or ice cream.