You’ve heard of rhubarb pie, but what about rhubarb cake? There are in fact variations that include rhubarb in custard cake, dessert cake, or berry coffee cake. You may call this recipe whatever you like, and serve it at any suitable occasion, but this is intended as a basic starting point. For instance, some people prefer it with twice as much rhubarb and a little less sugar.
Preheat oven to 375°F. Cream butter with brown sugar in a large bowl until light and fluffy. Beat in eggs, one at a time, then beat in vanilla and 1 tablespoon cinnamon. Sift flour and baking soda, and beat this mixture into butter mixture in three parts, alternating with buttermilk. Fold in rhubarb. Pour batter into standard 8" x 8" x 2" glass baking dish. Blend sugar and remaining cinnamon, and sprinkle over top. Bake until a toothpick inserted in the cake comes out clean (about 45 minutes). If the top starts to brown too quickly, lower the oven temperature to 350°F for the last 30 minutes. Top with whipped cream or ice cream.
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