Preheat oven to 350°. Lightly butter the pan or line with parchment paper.
Stir lemon juice into cream or milk. Set aside.
Cream together butter and sugar in mixer until fluffy. Beat in egg and vanilla, scraping down the bowl as necessary.
Mix 1 tablespoon of flour with rhubarb.
Whisk together flour, baking powder and salt.
Add half of flout mixture and blend well. All all of cream/milk and mix well. Then add remaining flour and blend until combine. Do not over mix.
Fold in rhubarb until blended. Do not over mix.
Spread in pan. Batter will be thick. Sprinkle with sugar.
Bake for 40-45 minutes until toothpick comes out clean.
Cool slightly before cutting.