In a small saucepan, gently warm 1 cup of whole milk over low heat until just steaming, about 3–4 minutes. Add 2 tablespoons of loose Earl Grey tea leaves, letting them steep for 10 minutes. Strain the mixture through a fine mesh sieve to remove the leaves, then allow the infused milk to cool to room temperature.

In a large mixing bowl, beat 1 cup of softened unsalted butter and 2 cups of granulated sugar together using an electric mixer on medium speed. Continue mixing for about 5 minutes, or until the mixture is light and fluffy.

Add 4 large eggs, one at a time, to the creamed butter and sugar, mixing well after each addition. Next, incorporate 1 teaspoon of vanilla extract followed by the cooled Earl Grey-infused milk. Mix until all ingredients are thoroughly combined.

In a separate bowl, whisk together 2 ½ cups of all-purpose flour, 1 tablespoon of baking powder, and ½ teaspoon of salt. Gradually add the dry mixture to the wet ingredients, mixing gently on low speed just until combined.

Preheat your oven to 350°F (175°C) and grease two 9-inch round cake pans with butter. Dust the pans lightly with flour to prevent sticking. Pour the prepared batter equally into the two pans.

Place the cake pans in the preheated oven and bake for 25–30 minutes, or until the edges are golden and a toothpick inserted in the center comes out clean.

Once baked, remove the cakes from the oven and allow them to cool in the pans for about 10 minutes. Invert the pans to transfer the cake layers onto wire racks. Let them cool completely before frosting.

In a medium bowl, beat together 2 cups of powdered sugar, 1 cup of heavy cream, and the zest of one lemon using an electric mixer. Beat on high speed until the mixture is light and fluffy, taking about 3–5 minutes.

Once the cake layers are completely cool, place one layer on a serving plate. Spread a generous layer of frosting over the top before adding the second cake layer. Frost the top and sides of the entire cake.