FOR THE CAKE: Place your 2 cups of milk in a small sauce pan, along with the cinnamon sticks, black pepper corns, cloves, cardamom pods, nutmeg and ginger. Bring it to a boil. Once it's boiling, turn off the heat, and add your 6 black tea bags. Put on a lid and let it go completely cool.
Preheat your oven to 180ºC/350ºF. Grease and line the bottom of two 22 cm (9-inch) round cake pans with parchmen paper. Set aside. In a large bowl, cream together your butter, sugar and oil, until light and fluffy. Add the eggs, one at a time, mixing very well after each addition. Sift in your flour, salt, baking powder and baking soda. Give it a nice whisk until almost combined. Fish your spices out of the milk and add it to the batter (leave the tea leaves in the batter or you can totally strain everything, if you want to). Mix until it's all combined. Pour the batter into the prepared pans and bake it for 30 to 40 minutes, or until a toothpick inserted in the center comes out clean. Let it cool completely once it's done.
FOR THE FROSTING: While your cakes are cooling, heat up the 1/3 cup of milk in the microwave until nearly boiling (or on the stove), add the content of the 2 cut open black tea bags, give it a mix and let it cool. In a bowl of a standing mixer, with the paddle attachment (or use a hand mixer), pour in your 220g of butter, give it a mix until it's smooth, then add your icing sugar, 1 cup at a time, beating until it's very light and fluffy (it'll also be very stiff). Add the 1/2 tsp of salt and 2 tbsp of your black tea infused milk. Mix again until combined. Now, it's up to you how you want this frosting to be: if you want it looser, add more milk, or add less if you like it stiffer, if you want it less sweet, add more salt, and keep adjusting, until you think it's good.
DECORATION: Take one of your cakes and place it on your serving platter. Take the other half and place it on a baking sheet, or anything like it (if you put random pieces of parchment paper in your platter before placing the cakes, it'll help you get a cleaner finish). Now, you can decorate this however you like. Take out the pieces of parchment paper and serve! This cake can also be made in advance, just leave it in the fridge and take it out about 20 minutes before serving.