Preheat the oven to 350ºF. Prepare your 9-inch cake pan by greasing it with pan spray or butter.
Using a stand mixer, beat the eggs, sugar, salt, and vanilla extract on medium speed. Beat for 20 minutes or until the egg mixture is pale yellow in color and thick/flluffy in texture.
Sift the flour. Add the flour to the egg mixture in 3 parts. Using a whisk, gently fold in the flour. Repeat this step 2 more times for the remainder of the flour.
Add the finely ground earl grey tea and fold it into the batter.
Transfer the cake batter to the greased cake pan. Do not tap the cake pan on the counter, to prevent any loss of the air bubbles.
Bake for 30 minutes. Do not open the oven door during the entire bake time (opening the oven door while it is baking, may cause the cake to deflate). The cake is done when a toothpick comes out clean when inserted.
Turn off the oven and allow the cake to cool in the oven for 10 minutes. Use a wooden spoon to keep the oven door slightly open.
Transfer the cake onto to a cooling rack and allow it to cool to room temperature before slicing into the cake.