Take a sauce to boil raisins in water and cook for 3-5 mins until raisins become soft.
Remove the pan from heat and cool it to room temperature then add pecans and walnuts into the raisins.
In a mixing bowl beat butter and sugar to make a smooth creamy mixture.
Now add eggs and vanilla and beat for 2-3 mins more so that the mixture becomes fluffy.
Using a flat rubber spatula mix flour and baking powder into the egg butter mixture so that a smooth batter would form.
After that add raisin, pecan and walnut mixture into the batter and stir well. Pour the batter in a greased baking pan of your own choice and bake at 350°F until become golden brown in color from top. It may take more than an hour to be done.