Revised rhubarb cake

The rhubarb is growing so fast that I sometimes don't have time to use it before it gets too wooden. But I had some sour cream that needed to be used before I had to throw it away so I decided to make rhubarb squares. My old recipe has a nice texture but is way too sweet so I thought I could improve it by using less sugar - and different sugars as well as adding almonds and ginger.

Mix until crumbly and set aside:
1/3 cup muscovado sugar

1 tsp. ginger
3/4 cup chopped almonds
1 tbsp. butter

Cream together:
3/4 cup raw sugar
1 cup butter
1 egg

Mix
2 cups all-purpose flour

1 tsp. ginger
1 tsp. baking soda

Add to creamed mixture alternately with
1 cup sour cream

Stir in
2 cups rhubarb, cut into ½-inch pieces

Turn into a greased 10x10-inch baking pan.Sprinkle with reserved topping. Bake in 350°F oven 45 to 50 minutes.