In a pot, combine milk and masala chai in loose leaf & spices format or teabags and bring to a simmer. Reduce heat to minimum and let steep for 7 minutes.
Strain leaves and spices or remove teabags. Bring milk back to the pot, add heavy cream, condensed milk and sugar and increase the heat a bit.
When it comes to a boil, reduce heat to simmer whisking constantly. Watch the edges because the milk will start to burn and turn dark so keep whisking and scraping the edges. If it gets too thick around the edges, remove those bits from the pot. It is ok to see bubbles on the edges of the pot but keep stirring constantly.
The spread is ready after 25-30 minutes or so when it's thickened, becomes darker and larger bubbles start to appear and move slowly allover. When you insert a spoon, the back will be coated and it will drip slowly like caramel.
Strain and pour into a glass container. Let cool completely before refrigerating.