Ingredients
1.5 cups white sugar
0.5 cup butter
1 egg
1 teaspoon vanilla extract
2 cups all-purpose flour
1 teaspoon baking soda
0.25 teaspoon salt
1 cup buttermilk
2 cups rhubarb, chopped
1 tablespoon all-purpose flour
1 cup packed brown sugar
0.25 cup butter
2 teaspoons ground cinnamon
Directions
Step 1
Preheat the oven to 175°C (350°F).
Step 2
In a large bowl, use an electric mixer to beat together the butter and sugar until the mixture becomes lighter in color. Then beat in the egg and vanilla extract.
Step 3
In a separate bowl, sift together 2 cups of flour, baking soda, and salt. Add this mixture alternately with the buttermilk to the butter mixture.
Step 4
Toss the chopped rhubarb with 1 tablespoon of flour, then gently stir it into the batter. Spoon the batter into a greased 9 x 13-inch pan and smooth the surface.
Step 5
Combine the brown sugar, 1/4 cup of butter, and ground cinnamon. Sprinkle this mixture evenly over the batter.
Step 6
Bake in the preheated oven for about 45 minutes, or until a toothpick inserted into the cake comes out clean and the top is golden brown.