• Line a 9x13-inch pan with non-stick foil or parchment.

Make the Chai Tea Infused Cream:

• In a small saucepan, heat the cream until it just begins to simmer. Remove from the heat, add the chai tea bag, and steep for at least 30 minutes or up to 1 hour for a more intense flavor.Remove the tea bag. If the bag has broken, strain the cream through a very fine-mesh strainer or cheesecloth to remove any tea leaves. set aside to cool.
  240 ml heavy cream, 1 chai tea bag
• Alternatively, if you plan to infuse the cream ahead of time (a day or two before) you can use a cold infusion method instead. Add the contents of the tea bag to the cold cream, seal tightly and store in the refrigerator for up to two days before straining the cream through a very fine-mesh strainer or cheesecloth to remove the tea leaves.

Make the Chai Tea Infused Butter:

• Place the butter in a medium saucepan. Break open the masala chai tea bags and add the contents to the butter. Heat gently over low heat, keeping the butter warm and liquid but not allowing it to boil, until it is very fragrant and has taken on a faint greenish hue. For a more pronounced chai flavor, remove the pan from the heat, cover, and allow the tea to steep in the butter for at least 10–15 minutes, or up to 30 minutes for stronger flavor (if it starts solidifying, place over low heat just until liquid again).
  336 g unsalted butter, 4 chai tea bags
• Strain the butter through a very fine-mesh strainer or cheesecloth, pressing the tea leaves and spices firmly to extract as much butter as possible. Set aside to cool
• Once the infused cream and butter have cooled, preheat the oven to 350°F.

Make the Cheesecake Batter:

• In a small bowl, whisk together the sugar, chai spice, corn starch and salt; set aside.
  75 g sugar, 1/2 tsp chai spice, 3 g corn starch, 1/4 tsp salt
• In a medium mixing bowl, beat the cream cheese, sour cream and chai tea infused heavy cream until smooth and creamy, with no lumps of cream cheese remaining.
  227 g cream cheese, 30 g sour cream, 30 ml chai tea infused heavy cream
• Add the sugar mixture and beat on low speed just until evenly incorporated. Avoid overbeating; you don't want to incorporate excess air into the cheesecake batter.
• Add the espresso powder, vanilla and egg and mix on low speed just until smooth and combined.
  1/2 tsp espresso powder, 5 ml vanilla, 1 egg
• Set the cheesecake batter aside while making the brownie batter.

Make the Brownie Batter:

• Whisk together the flour, cocoa powder, chai spice and salt in a small bowl. Set aside.
  120 g flour, 24 g cocoa powder, 1 1/2 tsp chai spice, 1 tsp salt
• Place the dark chocolate, chai tea infused butter, and espresso powder in a large microwave safe bowl. If your microwave has a chocolate melting feature, use that, otherwise, heat for 1 minute in the microwave, stir and then continue to heat in 30 second intervals, stirring after each interval just until the chocolate is fully melted. This can also be done over a double boiler.
  340 g dark chocolate, 224 g chai tea infused butter, 2 tsp espresso powder
• While the chocolate and butter are melting, beat the eggs, sugar and brown sugar on low speed until thick and syrupy. You aren't trying to aerate the eggs; the goal is to use the moisture in the eggs and steady mixing to dissolve the sugars (this is faster with an electric mixer, but can be done by hand). Whisk in the vanilla until combined.
  5 eggs, 200 g sugar, 110 g brown sugar, 15 ml vanilla
• Whisk the chocolate mixture into the egg mixture until a homogenous, glossy mixture is achieved. Rub a little of the mixture between your fingers; it should feel smooth rather than distinctly gritty.
• Add the flour mixture and stir just until it disappears. Reserve 1/4 to 1/3 of the brownie batter for swirling. Use closer to 1/4 for a more cheesecake-forward swirl, or closer to 1/3 for more visible brownie throughout the top (for a more brownie-dominant swirl, you can reserve up to 1/2 of the batter). If you are using the chocolate chips, fold them into the remaining 2/3-3/4 of the batter.
  113 g espresso, mocha or bittersweet chocolate chips
• Pour the larger portion of batter into the prepared pan. Pour the cheesecake batter over the top of the brownie batter in the pan. Pipe or dollop the reserved brownie batter over the cheesecake layer. Drag a butter knife through the batters a few times in alternating directions to create broad swirls. Stop while the cheesecake and brownie are still visibly distinct; over-swirling will muddy the pattern.
• Place the pan in the preheated oven and bake for 35–40 minutes. The edges should look set and may puff slightly, and the exposed brownie portions of the swirl may show a few small cracks. The cheesecake should remain smooth and should not develop cracks. Because the cheesecake layer is thin and the brownies are intentionally fudgy, a toothpick test is not a reliable indicator of doneness. Remove from the oven and allow to cool on the counter for about 30 minutes. Transfer to the refrigerator and chill for at least an hour or until the cheesecake swirl appears to be fully set.
• Remove the brownies from the pan (lift out using the foil or parchment paper) and cut into bars to serve.