Sieve all-purpose flour and custard powder into a large mixing bowl.

Mix well.

Add chopped cashew nuts and tutti frutti.

Mix to combine.

In another bowl, add butter and caster sugar.

Cream the butter and sugar well by whisking.

Add milk and whisk everything together.

Once well combined, add the flour mixture in batches, ensuring no lumps form.

Add a little milk if the dough is too dry.

Roll the dough into rectangular logs or desired shapes.

Cover with cling wrap and freeze for about 15 minutes or until firm.

Preheat oven to 180°C.

Remove the cling wrap from the dough and cut into even-sized biscuits.

Arrange cookies on a baking sheet with a 1-inch gap between each.

Bake in the preheated oven for about 15 minutes, or until the cookies start to darken in color.

Once cooled completely, store Karachi Biscuits in airtight containers.