Preheat oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
Heat milk until warm, then steep Earl Grey tea leaves in the milk for 10-15 minutes. Strain and discard tea leaves.
In a large bowl, cream together the softened butter and sugar until light and fluffy.
Beat in the eggs one at a time, then stir in the vanilla extract.
In a separate bowl, whisk together the cake flour, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, alternating with the Earl Grey-infused milk, starting and ending with the dry ingredients. Mix until just combined.
Pour the batter into the prepared cake pan and bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes before inverting it onto a wire rack to cool completely.
While the cake is cooling, prepare the frosting. In a large bowl, beat together the softened butter, powdered sugar, vanilla extract, and milk until smooth and creamy.
Once the cake is completely cool, frost it with the vanilla frosting.
Garnish with a sprinkle of Earl Grey tea leaves, if desired.