Now often made in cafes to be larger than a hand palm, the biscuit was once not much bigger than a penny.

The early 20th century recipe was crisp and oaty, but by the 1980s it had less oats, and chewy coconut added.

The basic biscuit was first devised as a nutritious and easily transported supplement for men on the frontline.

An Australian Imperial Force padre in 1915, John Fahey, said the biscuit's inventor was "an unmitigated rascal".

"As an eatable there is little to choose between it and a seasoned jarrah board," Fr Fahey was said to opine.

Based on a Scottish recipe, the "Soldiers' Biscuits" were renamed Anzacs after the Gallipoli landing in WWI.

By WWII, military ships had onboard refrigeration, so the need for self-preserving foods like the Anzacs was reduced.

Back home, the biscuits were sold at public events to raise money to support the war effort and, later, returned soldiers.

One hundred years on, the Anzac biscuit has been well and truly baked into Australia's heart as well as its history.

The Country Women's Association 1933 Calendar Cook Book, 'Cakes and Afternoon Tea Delicacies'

2 cups rolled oats

1/2 cup flour

1 small cup sugar

1/4 cup butter

1 tablespoon golden syrup

1 teaspoon carb soda

3 tablespoons boiling water

Put rolled oats and flour into basin: melt butter and sugar together and mix well with flour and oats; dissolve syrup in water and stir in soda till it foams well, then add to other ingredients and mix well. Put in 1/2 teaspoon drops on a cold, well greased slide and bake in a very a very slow oven, as they burn very easily. It is necessary to put them fairly far apart on the slide as they spread. (Supplied by Miss Murray, CWA Manildra Branch)

The Australian Women's Weekly's 'The Big Book of Beautiful Biscuits' (first published 1982)

1 cup rolled oats

1 cup plain flour

1 cup sugar

3/4 cup coconut

125g butter

2 tablespoons golden syrup

1/2 teaspoon bicarbonate of soda

1 tablespoon boiling water

Combine oats, sifted flour, sugar and coconut. Combine butter and golden syrup, stir over gentle heat until melted. Mix the baking soda with the boiling water and add to melted butter mixture. Stir into the dry ingredients. Place teaspoons full of mixture onto lightly greased oven trays; allowing room for spreading. Cook in a slow oven for 20 minutes at 150C / 300F. Loosen while warm then cool on trays. Makes about 30 biscuits.