If some Starbucks drinks are perfect for summer, chai is the best for the rest of the year. To make a Starbucks-esque iced chai latte at home, there are a few routes you can take. Hip2Save, for example, begins their recipe with chai tea bags, which they steep in hot water before adding milk, ice, and, optionally, sugar. However, an even easier version exists, as well as one that's completely homemade.
For an easier option that will taste most similar to Starbucks' latte, grab a box of shelf-stable chai concentrate from your local grocery store or order some online (via Sweet Steep). The Tazo brand's concentrate will get you the closest to Starbucks' taste, but any brand of chai concentrate will work. To make an iced latte with a concentrate, you simply pour some concentrate into a cup and top with ice and milk. It comes together in seconds, and you can adjust the strength and caffeine levels based on how much concentrate you add, so you're in full control.
However, if you want to make a completely homemade chai latte, you'll need to start with straight black tea, whether in bags or loose leaf. On the stove, boil your tea in water and add warm spices to infuse. Taste of Home recommends incorporating cinnamon, ginger, and allspice. Then, you can make a sweetened cream with brown or granulated sugar to latte-ify your tea when it's done. Taste of Home notes that this process can be expedited by steeping the tea and spices in a coffee machine.
Happy drinking!