• in a bowl mix the maizena (corn starch) with 1 cup of the milk at room temperature, mix well until fully dissolve.
• In a heavy bottom pot add the remaining milk, when the milk start is hot add the jaggery powder(panela), add the spices to your taste. you can start with the measures suggested here for cinnamon, cloves and Nutmeg.
• when the jaggery or panela is totally dissolved add to the pot the mixture of milk with Maizena and stir without stopping until the Natilla has a thick consistency.
• Then add the butter and continue stirring for another 5 minutes until the butter is complete melted.
• Remove from the fire and transfer to a heat proof container. Let it cool and refrigerate. Cover with a film or lid when it is completely cool.

You can use also cinnamon stick but you need to remove them before to transfer the Natilla into the final heat proof container.