Preheat oven to 180 degree C. Grease a 9x5 inch loaf pan with oil and dust it with flour. Coat on all sides and set aside.

Now take butter, sugar and vanilla in a bowl and whisk well. Now add in eggs one at a time and whip till creamy.

Now add in flour, baking powder and salt and fold gently. Add in milk and fold gently.

Divide the batter between 6 bowls and add one food colouring in each one and mix well. Now spoon this into the loaf pan and use a skewer to make swirls on it.

Now bake this in oven for 45 mins to 1 hour till the cake is done.

Remove it and cool down completely. Slice and serve.