Filling:
In a medium saucepan combine sugar and cornstarch. Stir
in rhubarb.
Cook
and stir over medium heat, until mixture comes to a
boil and thickens. Remove from heat and cool.
Cake:
Combine milk and lemon juice. Set aside.
Combine
flour and sugar. Cut in butter until mixture is crumbly
( a food processor is great for this). Remove 1/2 cup
of this mixture and set it aside to use for topping.
To
the remaining flour mixture add baking powder, baking
soda, and walnuts.
Combine
egg with milk mixture. Add to the dry ingredients and
stir or process until just moistened.
Spread
2/3 of the batter over the bottom and part way up the
sides of a greased 9 inch springform pan. Spoon the
rhubarb filling over this. Drop the remaining batter
by spoonfuls over the filling. Sprinkle with reserved
crumb mixture.
Bake
at 350 degrees for 50 minutes.
