The TLDR: Jessica does things the hard way, reviews baking science 101. For the past three weekends, I've been experimenting with Thai tea flavoring in desserts, brewing straight from whole spices and loose tea leaves - no tea bags! This is the closest I've come to a really satisfying result that has both the flavor and color without the use of dyes, although I'd like to continue tweaking the base milk cake recipe itself to improve texture. (Nerdy ruminations on food science to follow - feel free to skip through and just look at the pictures).
The options for infusing tea into your desserts are as follows: 1) whole tea leaf method, where a few tablespoons of tea leaves are mixed straight into the batter or custard, 2) infuse the butter, or 3) infuse the milk/cream. I found that #1 doesn't release the flavors or colors very strongly and you may end up using more tea to compensate, which is a waste when using good quality product. #2 requires that you melt the butter, which may be fine for some recipes; however, for any dessert where you cream butter and sugar together, this is not suitable. Even if the butter is cooled and re-hardened, it won't cream nearly as well, resulting in an un-aerated cookie or cake. My guess for the reason why: butter is a colloid where insoluble fats are dispersed through liquid, and it's well-understood that melting separates the fat and liquid almost irreversibly. This unstructured, separated mixture does not have the ability to hold air in the same way that cold butter does. (Think about how unstable bubbles in a glass of water are). Does this have any scientific validity? Chemists, please weigh in.
This left me with option #3: infusing tea leaves and spices into milk. Milk and cream-based dessert options include flan, panna cotta, creme brulee, and milk cake. I tested a Thai tea flan but wasn't impressed by the coloring; it came out a really weak, unappetizing brown hue. To be fair, the tea-infused milk is actually that color, but I had hoped for something a little more vibrant. (Side note: Thai tea is made from Ceylon tea and a variety of added spices... but the tea bags also contain a good amount of food coloring. Ceylon, when brewed, is naturally a little bit reddish-orange, but the color you see in store-bought beverages is highly exaggerated). I figured that panna cotta and creme brulee might have the same issue, so I began looking into some basic milk cake recipes. The extra caramelization you get on the side of the baking dish in a cake typically carries more color oomph.
I wanted to really let the tea flavor shine so I searched for a cake recipe that had the highest proportion of milk to flour. I adapted this recipe, reducing sugar and increasing milk as recommended by some comments (in addition to flavoring the milk as described above). The reduction in sugar is largely because it's just way too sweet with a whopping 2 cups of sugar, but you actually compromise texture if you don't make the milk adjustment. When flour and water are combined, gluten is formed - chewy and strong and delicious in bread but a disaster when in excess in pancakes, muffins, and cakes. Sugar limits this by binding with the liquid molecules, making them unavailable for gluten production. So cutting sugar in half, without any other adjustments, results in a tough cake. Milk has a good amount of fat and lactose which can limit gluten formation, so it's a decent (although imperfect) substitute. Oil can be used as well for the same purpose.
The cake had less sponginess than I had hoped for, though. This is definitely fixable the next time around - the main culprit here being the ever-feared gluten. Strongly recommend using cake flour rather than all purpose which has lower protein content and therefore will result in less gluten. Also, overmixing will always result in a chewier cake, so mixing by hand definitely preferable after the eggs and milk have been beaten to the requisite airiness (I was using a borrowed Kitchenaid stand mixer, which I'm not quite used to yet). Finally, I was really excited to try a 4-inch tall x 6 inch diameter cake pan for pretty proportions without dealing with layers, but I have to admit that the shortcut compromises texture and you are better off going with two pans and a Victorian Sponge visual approach.
Recipe, and my recommendations for the A+ version, below!
Thai Tea Milk Cake Recipe (serves 8-10) (base cake recipe loosely adapted)
- 1 1/4 cup milk
- 2 heaped tbsp Ceylon tea leaves
- 1 star anise
- 2 lightly crushed cardamom pods
- 1/4 tsp tamarind (optional)
- 2 cloves
- 1/2 cinnamon stick (or 1/2 tsp cinnamon)
- 1.5 tsp vanilla
- 2 cups flour - use cake flour!
- 1 cup sugar (I actually think that up to 1 1/3 would not be too sweet. Bakers often refer to an ideal 1:1 flour to sugar ratio by weight for proper texture, with ~20% room for variance, which means 1.5 cups of flour for every 1 cup of sugar. 1 1/3 cup sugar to 2 cups of flour would be right at this ratio)
- 2 tsp baking powder
- 4 eggs at room temperature (to speed up this process, add them to a bowl of warm water!)
- Optional toppings: 1/2 cup whipped heavy cream (I add 1/4 tsp sugar to stabilize once whipped to soft peaks level), 1 ripe mango, crushed and simmered down into concentrate, slivered almonds
Preheat oven to 350 degrees. Line the bottom of two 9 inch round pans with parchment paper, but do not grease the sides of the pans. Egg-aerated sponges need to cling onto the sides in order to rise!
Sift together baking powder and cake flour.
Scald the milk just until steaming and bubbles are forming. Turn off the heat and add in the tea leaves, star anise, cardamom, tamarind, cloves, cinnamon stick, and vanilla. Steep for ~20 minutes.
Meanwhile, whip the eggs. When they begin to start looking foamy (~3 min), add in the sugar gradually down the side of the bowl, whipping the whole while. The mixture will start to look pale, lemon yellow, and thick as air is beaten into the eggs. At this stage, add in the flavored milk gradually through a strainer to ensure no solid spices end up in the mix, beating on medium speed.
Hand-mix at this point, using a wooden spoon or whisk so that the minimum amount of air is knocked out of the eggs. Add in the sifted cake flour and baking powder 1/3 at a time, folding in gently. Once just incorporated, stop mixing.
Pour into prepared pans and bake for 22-25 minutes, or until a skewer inserted at the center comes out clean. Cool for 10 minutes, then invert onto a plate and wait until the cakes are at room temperature before decorating. This goes very well with any tropical fruit and a lightly sweetened cream.