You can find a nice-looking recipe
here, all the way from India. The spice mix is under the title "Ingredients for Masala Chai" (masala meaning a spice mix).
Otherwise, you can mix together all this and keep it in a jar that closes really well:
6 allspice berries
2 Tbsp of cardamom seeds (remove husks)
6 Tbsp cinnamon bark, roughly crushed (wrap in cloth and use hammer on it)
1 Tbsp of coriander seed
25 black peppercorns
3 Tbsp of fennel seeds
To make up the tea, bring softly to a boil 170 ml milk with 4 Tbsp sugar and 500 ml water plus one more or less heaping Tbsp of the spice mix. When it boils, remove from fire, cover and steep for 3 minutes. Add 1 Tbsp black tea, let steep for 3 more minutes. Filter and serve in cups.
I must now confess I am now using a mix I brought back from India a year ago, I save these for when I finish it.