Preheat the oven to 320 degrees F (160 degrees C). Line two 9-inch cake pans with parchment. Spray the cake pans well with Nonstick Cooking Spray (to taste).
Combine Self-Rising Flour (250 gram), tea leaves from 1 teabag of Earl Grey Tea (1 bag), and Baking Powder (1 teaspoon) in a bowl and set it aside.
Set up a stand mixer and fit it with the whisk attachment. Combine Caster Sugar (250 gram) and Unsalted Butter (250 gram) in its bowl and beat them together until fluffy.
Add in the Egg (5) one at a time, followed by Pure Vanilla Extract (1 teaspoon). Let it all get whipped up on a higher speed for a minute, then turn off the mixer.
Pour the dry ingredients into the bowl through a fine mesh strainer so that it is very fine and light. Fold it in with a spatula.
Fold in 1 teaspoon of zest from the Lemon (1), Ground Lavender (1 teaspoon), and Milk (1/4 cup) to moisten it.
Divide the batter evenly among the two prepared cake pans and bake the layers for 25 to 30 minutes. Do not open the oven door or turn on the light until 25 minutes in to check them. Let them cool completely.
While the cakes bake and cool, make the earl grey syrup. Combine Water (1/2 cup), Caster Sugar (1/2 cup), Earl Grey Tea (1 bag), and Pure Vanilla Extract (1 dash) in a saucepan and heat it over medium high heat.
Let it come to a gentle boil while you stir it. Once it starts to coat the spoon and thickens into a syrup, take it off the heat to cool.
Make the whipped cream. Combine the Heavy Cream (16 fluid ounce), Caster Sugar (2 tablespoon), and 1 teaspoons of zest from the Lemon (1) in a mixing bowl and use a hand mixer to whip it up into stiff peaks. It should be airy but not runny at all. Then it is time to assemble this baby!
Place the first layer flat side up on a cake plate and poke holes all over it. Drizzle in half the syrup to soak into the sponge. Then spread half the whipped cream on it evenly.
Place the second layer on flat side down. Poke holes and drizzle the remaining syrup into the sponge. Spread the remaining whipped cream on top, then sprinkle remaining 1 1/2 teaspoon of lemon zest and Ground Lavender (1 teaspoon) on top. Serve and enjoy!