For spice-infused base

Cup of Yum
1. Place the milk and cream in a heavy based pot/pan and add the whole spices - cinnamon stick, star anise, cardamom, cloves, allspice, peppercorns and slices of fresh ginger.
2. Warm the mixture over a medium low heat for around 5 - 10 minutes, until the mixture is warm but not boiling. Remove form heat and leave to steep around 45 minutes.

For rest of ice cream

1. Add the tea bags to the spiced milk-cream base, along with around half of the sugar. Warm again for a couple minutes to re-heat but again without simmering, then leave to steep around 10 minutes. You should notice the color becoming quite a bit darker.
2. Whisk together the egg yolks and remaining sugar in a small bowl until well combined and slightly glossy.
3. Taste a little of the milk-cream base and if needed, add a little ground masala chai spice to boost the spice flavors. Re-warm the milk-cream mixture over a medium heat until it is starting to steam slightly but just below reaching a simmer.
4. Carefully add a small amount (around a couple tablespoons or so) of the warm milk-cream mixture to the yolk mixture and whisk as you add so it combines without cooking the egg. Once mixed, add a little more, mix then repeat.
5. After you have added the warm milk around three or four times, pour the eggy mixture in to the main pot/pan. I suggest removing the tea bags at this stage, though you can leave a little longer if you prefer. Place the pot back on the stove over a medium-low eat. Warm the mixture, stirring constantly, so that it thickens up a little. Take care - DO NOT BOIL. It should warm to around 170F/76C. It won't thicken all that much but at least a little.
6. Strain the mixture through a relatively fine strainer to remove all the spices and any other solids then let the cream mixture cool. After it is cool enough, place in the fridge to chill at least a few hours but ideally overnight.
7. Once chilled, follow your ice cream maker's instructions to churn the mixture to a soft serve consistency. Once soft-serve texture, add in the chopped crystalized ginger pieces, churn briefly to mix then transfer to a container and place in freezer for a few hours to firm up before serving.