Cream the margarine and sugar together until it turns white.

Add the beaten eggs gradually while whisking.

Sieve in the flour while whisking till it's well incorporated.

Now blend the mint and add in some green food colour to add brighter colour to the mint.

Fold in the blended mint into the mixture till it mixes well.

Grease the tin and add the in the mixture and put in the oven to bake.