1. Grease a 9-inch cake pan and set aside. Preheat the oven to 375 degrees F. 

To make the topping:

  1. In a medium bowl, combine rhubarb, ½ cup sugar and 2 teaspoons corn starch. Stir to combine and place in bottom of prepared cake pan.  
  2. In a small bowl combine melted Kerrygold® salted butter and brown sugar and stir to combine. Drizzle over rhubarb mixture. 

To make the cake:  

  1. Place butter and sugar in another medium bowl and beat until combined. Add egg and vanilla and beat until thoroughly mixed. 
  2. Add cinnamon, baking powder and ½ cup of the flour and beat until just combined. Add ¼ cup of the milk and beat until just combined. 
  3. Add ½ cup of flour and beat until just combined. Add ¼ cup milk and mix. Add remaining 1/3 cup of flour and stir until just combined. 
  4. Pour cake batter over rhubarb mixture and bake in preheated oven for 35-40 minutes or until toothpick comes out clean. 
  5. Cool on rack for 15 minutes and then invert on serving platter. Serve warm with crème fraîche, if desired.