Begin by preheating your oven to 350 degrees Fahrenheit. Lightly grease and line with parchment paper (with two sides hanging out) an 8-inch square pan (for a thicker cake) or a 9 x 13 baking pan.
In a medium saucepan, add the milk and tea bags over medium-high heat until it comes to a boil. After it reaches a boil, turn off heat and let tea bags simmer (while covered with a lid) to allow everything to infuse together and milk to cool down, about 10-15 minutes.
In a medium-sized bowl, whisk together the flour, baking powder, cinnamon, and sea salt until combined. Set aside.
In a large bowl, add together the sugar and unsalted butter, mixing by using a hand-mixer on medium-high speed, until fluffy and airy, about 2-3 minutes.
Add in the eggs (one at a time), vanilla, honey, and the milk-tea bag mixture (saving 3 Tbsps for later), followed by the dry ingredients, mixing everything together until well combined, smooth, and lump-free, about 2-3 minutes.
Pour batter evenly into prepared pan, spreading everything around for a perfect evenness.
Bake for 20-25 minutes, or until the center of the cake comes out clean when tested with a toothpick or butter knife.
Once done, remove the cake from the oven and let cool for 30 minutes before carefully lifting it from the pan and unto a cooling rack to cool completely.