Finely chop the walnuts and combine with the coconut. Microwave on high for 1 minute, stop, stir and microwave for a further 1 minute. Set aside.
Trim the ends of the rhubarb and chop into 3cm pieces. Place rhubarb, butter, sugar, water and cinnamon. Cover, and microwave for 10 minutes.
While that is cooking, zest the rind of the lemons, and juice them.
With electric beater, whip the egg whites until it forms fluffy peaks, set aside.
Cream the butter, sugar and lemon zest until fluffy. Beat in the egg yolks.
Slowly blend in the flour, followed by the lemon juice, then the milk. Mix well.
Gently fold the egg whites into the lemon batter until well combined. Do not over mix.
Pour into a microwave safe dish, sprinkle over the coconut & nut topping, and microwave for 10 minutes.
Remove from microwave, cover, and let stand for 5 minutes.
Serve topped with the rhubarb, and a dollop of cream.