Preheat oven to 170 deg celsius.

In a mixing bowl add softened unsalted butter and beat until creamy.

To this add powdered sugar , custard powder and beat until light in texture.

Place a sieve above the mixing bowl , add app purpose flour , baking powder and pinch of salt.

Sift flour directly over the mixing bowl.

Mix everything with a spatula.

Scoop ½ tablespoon of cookie dough , shape them with hands , press them lightly and place on a prepared baking tray.

Bake butter cookies at 170 deg celsius for 16-18 minutes.

Remove from the oven , transfer cookies over a wired rack to cool.

Whilst biscuits are baking, prepare citrus cream filling.

Finely grate orange to get 2 teaspoon of orange zest. Be careful while grating, you shouldn't grate white part of the orange.

Cut orange and squeeze to get fresh orange juice.

Into a mixing bowl , add softened unsalted butter, icing sugar , orange zest and orange juice.

Whisk well briskly to make the cream smooth and light.

Once the creamy turns silken and smooth , fill into a piping bag.

Once the biscuits are completely cool, pipe citrus cream on to the flat side of the biscuits.

Cover with another biscuit and serve.

You can store these cookies in a airtight box.