Note 1.  (If you have not butter milk you can use substitute of butter milk. Place a tablespoon of white vinegar or lemon juice in a liquid measuring cup. Add one-cup milk.Let stand for five minute. This is butter milk.)

1. Preheat the oven to 180 C and grease 9" inch pan with oil or butter.
2. Mix dry ingredients-flour, baking powder and salt in a bowl. Mix with a hand mixture.
3. In a separate bowl whisk egg with a electric bitter until creamy texture. Add powdered sugar a little by little and continue whisking.
4. Then add oil and continue beating. Then add butter milk,vanilla and keep whisking till creamy texture.
5. Now gently mix dry ingredients with a spatula. Mix just well combined.
6. Pour the batter into cake pan. Spread with spatula as evenly as possible, pushing batter into corners of pan. Jiggle vigorously till batter is level. Bake for 45 minutes. Check with a wooden toothpick.
7. Remove from oven. Peel parchment paper from bottom  of cake. Let it cool on a rack.