Plain vs flavored Crema Catalana

I have in front of me two recipes for Crema Catalana, one plain and one coffee and cardamom flavored.

The amount of milk in the former is equal to the amount of milk plus coffee of the latter. The other ingredients, i.e. yolks, sugar and cornstarch are the same in both.

The directions for the plain Crema go as follows. Whisk the yolks with half the sugar and, aside, mix a small part of the cold milk with the starch. Add the cold milk plus starch mixture to the yolks.

Bring to boil the remaining milk with the remaining sugar and flavors (cinnamon and lemon), filter it on the cold mixture and take everything back to heat to boil for a couple of minutes. Then put in ramequins and let cool.

The direction of the flavored Crema say to first heat the milk, half the sugar and the starch, then add the cardamom to and the coffee and let thicken, then filter this on the yolks mixture. Mix, and put back on heat for a couple of minutes. Then put in ramequins and let cool as above.

Is there a reason for the slightly different directions? What's the point of cold starch mixture vs hot?