1. Roast walnut in 325°F (160°C) oven 10-15 minutes or until fragrant and lightly browned. Grind walnuts to powder in blender.
2. Combine walnut powder, rice flour, sugar and water in a large sauce pan and slowly bring to a boil. Reduce heat to low and simmer, stirring continuously for 15-17 minutes.
3. Stir in milk and bring to a second boil.