Melt the butter with double boiling method for later use. Beat the eggs, add in caster sugar and mix, then add in milk and melted butter and continue to mix.
Add in the beaten eggs to the sifted self-raising flour and mix it, add in oreo crumbs and mix well.
Pour inside the baking cup lined with baking paper, each 80% full, then place the oreo biscuit and press it in lightly. Put it in the oven at 180 degrees for 25 mins.