Preheat oven to 350 degrees F.
In a bowl mix eggs and ⅔ cup of sugar until light.
Add melted butter, vanilla, and milk.
Stir in flour, baking powder and salt and mix to combine.
Pour into a 8 or 9 inch cake pan that has been sprayed with nonstick cooking spray.
Spread diced rhubarb around the top of the batter and sprinkle with 2 tbsp sugar.
Bake at 350 degrees for 30 minutes or until a knife comes out clean.
