Combine cake flour, baking powder, and salt in a bowl.
Add cold unsalted butter and cut into small pieces with a scraper, then rub together with your hands until evenly mixed.
Add sugar, lemon zest, and Earl Grey powder; mix well.
Mix together egg, milk, and lemon juice, pour into the dough, and quickly mix with a spatula.
Roll out the dough to a thickness of 2 cm and cut into mini size pieces.
Place on a baking tray, brush with egg wash, and bake in a preheated oven at 180°C for 20 minutes.