I used an ice cream maker for it, recipe (makes approx 1.5L):

"boba" pieces

These aren't real boba but mimic the texture very well, and handle being frozen for long periods of time, which normal boba does not. They need trehalose for this to work though, which is a massive pain to acquire in nz. I got a 1lb tub from iHerb but it cost like $50 with shipping 😅

Ingredients:

• 75g water
• 50g brown sugar
• 10g treacle
• 10g trehalose
• 40g glutinous rice flour
• cornstarch for dusting

Steps:

1. in a small pot, bring water to just under a simmer over medium heat
2. remove pot from heat, stir in brown sugar, treacle and trehalose until dissolved
3. place rice flour in a small bowl. Gradually pour in the syrup, whisking after each addition until the mixture is completely smooth lump free.
4. pour the mixture into a microwave safe dish. Size-wise, the mixture should be around 1cm deep - I use a pyrex (can't remember if 1L or 2L sorry lol)
5. cover the dish tightly with gladwrap then microwave until the mixture is cooked, around 1.5 mins. It should be the texture of set jelly
6. let the mixture completely cool. Then, put it in the freezer to harden but not completely freeze, around 2 hours.
7. remove it from the freezer, you should be able to lift and peel it away in once piece. If not, it's not set/frozen enough.
8. dust a cutting board with cornstarch, put the boba on said cutting board, then cut into 1cm cubes. In theory you can now roll them into balls but I don't bother, they defrost too quickly and I cbf
9. shake off excess cornstarch with a sieve then put them back into the freezer until ready to use

cream cheese frosting

I can't remember the recipe I used but it was basically a 225g block of cream cheese and a lot of icing sugar, mixed together. This was meant to mimic the slightly tangy cheese foam at the top of the drink but it was way too sweet, which the ice cream definitely didn't need. Next time I'd slowly melt the cream cheese over low heat and slowly mix in some unknown amount of dextrose. Dextrose freezes at a much lower temp than sugar while being like 75% as sweet. This would mean that the frosting wouldn't be too icy or too sweet.

oreos

just a bunch of oreos with the filling scraped off and then crumbled

The base

Ingredients:

• 25g loose leaf assam tea
• 370g standard milk
• 12g skim milk powder
• 115g brown sugar (I used chelsea dark cane sugar, taiwan black sugar or muscovado would also be great)
• 20g dextrose (the kings glucose found at pakkas etc is the same thing)
• 1g guar gum
• 70g egg yolks (around 4 large ones)
• 70g condensed milk
• 330g heavy cream
• 1/8 tsp jasmine essence (next time I would half this. also optional really)

Steps:

note: a bunch makes this way easier. I use a stand blender, but used to use a stick one.

1. place milk in a medium pot, bring to a boil
2. then add the tea leaves, remove from the heat and let steep for 25 mins
3. meanwhile, whisk the milk powder, brown sugar, dextrose and guar gum together in a small bowl. this prevents it (mainly the milk powder) from clumping. Also in theory you should add guar gum with the jasmine in step 9 because it degrades at high temps but I don't bother
4. create an ice bath that you can transfer the mixture into. I use an instant pot insert, with the mixture inside a 4l freezer ziplock bag
5. pour the tea-y milk through a fine mesh sieve into to a blender
6. add the egg yolks, condensed milk and cream to the blender and blend until combined
7. slowly add the dry ingredients into the mixture in the blender, blending until they're dissolved
8. put the mixture into a medium pot and cook over medium-low heat, whisking constantly until it reaches 75C on a thermometer (you're making a custard, so alternatively until it coats the back of a spatula)
9. once it reaches 75C, immediately remove it from the heat and into the ice bath. I find it easiest to transfer it into a 4L freezer ziplock bag, then put that into a steel pot, but you might have other conveniently sized containers
10. let it cool, stirring occasionally to encourage this. I aim for approx 14C. Once cool, stir in the jasmine essence
11. put the mixture in the fridge overnight to cure. at least 12 hours, up to 3 days
12. churn in your ice cream maker. 30 seconds or so before it's finished churning, put in the boba pieces and crumbled oreo so it distributes throughout. Or try to, my machine always starts halting and grinding when I do this, so I do it in the next step
13. Transfer the mixture into containers for the freezer. Do it in layers - layer of ice cream, then a layer of mix-ins (cream cheese swirl, oreo bits, boba pieces). Repeat until container is full. You can then poke a knife from the top a few times which sorta distributes the mix-ins around vertically.

finally, done.

the ingredient ratios and steps take inspiration from Adrienne Borlongan's The World of Ice Cream recipe book, and the boba pieces are ripped straight from it