1. Put rhubarb pieces, 1 tbs of the Natvia and water in a saucepan; gently bring to the boil. Reduce heat to a simmer; cover pan. Cook until rhubarb is soft and just starting to lose its shape, 7 to 10 minutes. Remove from heat and set aside to cool.
2. Pour milk and vanilla extract into a heavy-based saucepan; heat until almost boiling. Remove from heat and set aside.
3. Whisk egg yolks, then add remaining Natvia and cornflour. Gradually add hot milk to egg mixture, whisking to combine.
4. Return mixture to pan; stir over very low heat until it thickens, about 4 minutes.
5. Remove custard from heat and transfer to a blender. Add yoghurt and pulse until smooth.
6. Fold rhubarb through custard cream. Divide among 4 serving bowls, lightly sprinkle with chopped pistachios and serve.
Nutritional Info per serving
1,081 kJ (258 cal), 12g protein, 15g carbs, 3g fibre, 15g fat (6g sat fat), 92mg sodium