Line a rectangular 12u201d by 8u201d tin with aluminium foil or parchment paper.
Put the condensed milk, chocolate chips and butter in a large thick walled pan. Place the pan over another pan of boiling water such that the bottom of the first pan doesnu2019t touch the water. Stir the milk-chocolate-butter mixture well till the chocolate has melted and the mixture is smooth.
Take this pan off the pan of boiling water and place it on the stove, over low heat. Add the cinnamon and chai masala and stir frequently till it thickens a little and appears to be coming away from the side of the pan (about 5 minutes at the most).
Take the pan off the heat and fold in the toasted nuts. Pour the fudge into the lined tin and level the top. Place in a cool for about 4 to 6 hours or overnight to set well. To unmould, turn the pan upside down over a board and peel off the foil or parchment paper. Cut into about 1 1/2u201d squares.
Store in a container, stacked in layers separating each layer with a sheet of foil or parchment paper. Refrigerate till ready to serve. This recipe makes about 24 fudge squares (1 1/2u201d squares).