This creamy, fluffy rhubarb custard cake is so simple to make and is a lovely recipe for spring!
Preheat the oven to 350 degrees. Grease and lightly flour a 9 x 13 inch cake pan.
Place the rhubarb in a bowl and sprinkle sugar over top. Allow to sit while you prepare the other ingredients. Prepare the cake mix according to package instructions then pour the batter into the prepared pan. Toss together the rhubarb and sugar then sprinkle evenly on top. Pour the cream over the entire top.
Place the cake in the oven and bake for 45 minutes to 1 hour, or until top is set and a toothpick comes out clean (the bottom third of the cake will still be wet so don't base the toothpick test on that portion). Serve the cake warm (it will be messy!), or chill for a few hours or overnight to have neater slices.