Preheat oven to 160°C.
Place the rhubarb with raw sugar into a small roasting tin, and roast in a 160°C oven for 30 minutes until fragrant and juicy. Toss with the frozen raspberries immediately and set aside.
Butter and line a 10 inch springform pan and set aside.
Make the base and press into the prepared tin, making sure it is pressed down firmly.
Bake the base for 15 minutes until fragrant.
Without cleaning Thermomix bowl, blend all filling ingredients except fruit until smooth and creamy.
Pour the mixture into the base to almost the very top.
Gently put fruit on top of cheese filling and try to distribute evenly throughout cake, marbling as you drizzle juice into it.
Bake in oven for around 50 minutes or until middle is set when you shake it. Leave in the oven until almost cooled with the door slightly ajar.
Chill completely.
Spread the top with whipped or double cream and then top with more of the stewed fruit to serve.