For the Rhubarb Cake
2 cups all-purpose flour
1 teaspoon baking soda
1/2 teaspoon kosher salt
1/2 cup unsalted butter
1 1/2 cups sugar
1 teaspoon vanilla
1 large egg
1 cup buttermilk (or substitute 1 cup whole milk with 1 tablespoon cider vinegar)
2 1/2 cups chopped rhubarb (about 4-5 stalks, depending on size; don’t skimp)
cinnamon sugar (1 tablespoon granulated sugar and ¼ teaspoon cinnamon, combined)
For the Whipped Cream
1 cup heavy cream
1/4 cup granulated sugar
1/4 teaspoon vanilla
Preheat oven to 350 degrees. Lightly grease a 9×13 cake pan with butter and set aside.
Sift or whisk together flour, baking soda and salt in a bowl and set aside. In the bowl of an electric mixer, mix the butter and sugar together until creamy. Add vanilla and egg, and mix well. While the mixer runs, alternately stir in buttermilk and flour mixture in batches, ending with the flour mixture, until the batter is just combined. Add rhubarb and stir.
Spread the batter into the prepared 9×13 inch cake pan. Sprinkle the top with cinnamon sugar. Bake for 35 minutes or until the cake is golden brown and a toothpick inserted in the center comes out clean.
While the cake bakes, make the whipped cream. In a cold mixer bowl (I like to put my mixer bowl and whisk in the freezer beforehand), whisk the heavy cream until soft peaks form, and gradually add in the sugar and vanilla. Store in the refrigerator until ready to serve.
When the cake is baked, allow to cool on a wire rack. The cake is delicious warm or at room temperature. Serve with a dollop of whipped cream.