Preheat the oven to 170°C (338°F).
Melt dark chocolate and butter together using a double boiler.
Infuse the aroma of Earl Grey tea by steeping a tea bag in milk.
Whip eggs and sugar until fluffy.
Mix the melted chocolate and butter, milk, and whipped eggs and sugar.
Sift cake flour and cocoa powder into the mixture and fold quickly.
Pour the batter into the pan and smooth the surface.
Bake in the oven at 170°C for 25–30 minutes.
Let cool, then cut into pieces to serve.