Grandma Donna’s Rhubarb Cake


This cake is a bit of a legend in my family. My maternal grandmother has made it for as long as I can remember and everyone LOVES it. It’s one of those cakes that you always eat two pieces of and then yearn for a third (and depending on willpower levels that day, may actually have it). I have many memories of being a little girl and feeling really grown up while having this with milky afternoon tea at grandma’s house; that first bite is nostalgic every time. This year when I bought a little rhubarb plant in early Spring I hoped and prayed to end up with enough to make at least one rhubarb cake. Fortunately, I got about 8 cups of diced rhubarb and in truth, this is probably all I’ll make with it. Fine by me! This cake consists of a really simple and moist buttermilk base dotted with tart rhubarb and covered with a cinnamon sugar sprinkle that creates a crackly top when it bakes. Recently my Grandma was asked to bring it to a family birthday party. In addition to her cake was one of those crazy looking confections covered in plastic-looking fondant. Which cake did everyone choose? Grandma’s rhubarb cake won by a landslide. It just tastes like home. Give this one a try; it’s famous for a reason!

Grandma Donna’s Rhubarb Cake

Makes one 9×13 cake



  • 1 1/2 cups brown sugar
  • 1/2 cup white sugar
  • 1/2 cup softened unsalted butter
  • 1 egg
  • 1 cup buttermilk
  • 1 tsp. vanilla extract
  • 1/2 tsp. salt
  • 1 tsp. baking soda
  • 2 cups all-purpose flour
  • 2 cups diced fresh rhubarb


  • 2 tbsp. white sugar
  • 1 tsp. cinnamon


Preheat oven to 350 degrees. Grease and flour a 9×13 pan and set aside.

In your stand mixer, cream the butter and sugar until light and fluffy. Stir in the egg until mixed well. Add the buttermilk and vanilla and stir again. Batter might be a little lumpy. Add the dry ingredients and stir until just moistened. Stir in the rhubarb. Spread batter into pan. For the topping, stir together the sugar and cinnamon and sprinkle evenly over top of the batter. Bake for 40-50 minutes or until a toothpick inserted in the center of the cake comes out with a few moist crumbs clinging to it.


I never have buttermilk on hand so I always just put 1 tbsp. of lemon juice in the bottom of a measuring cup and fill the rest with milk. Stir and let sit for a few minutes. Buttermilk!

My rhubarb was frozen and then thawed; because of this, I added about 3 1/2 cups with success. Drain thawed rhubarb of excess liquid before adding to the batter.


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