Prepare the Pan: Brush a Pyrex pan with ghee or butter, dust with 2 tablespoons of flour, and shake off any excess.
Sift Dry Ingredients: Sift together 2 cups of flour with a tablespoon of baking powder.
Mix Wet Ingredients: Beat together 3 eggs, 1 cup of sugar, and a small spoon of vanilla for 5 minutes until the volume doubles.
Combine Wet and Dry Ingredients: Add 1/2 cup of milk and the oil gradually while mixing at a low speed. Then slowly add the flour mixture, mixing until just combined.
Prepare Chocolate Mixture: Take a cup of the batter aside and mix with 2 tablespoons of cocoa powder and 2 tablespoons of milk until smooth.
Create Marble Effect: Pour the vanilla batter into the pan, then dollop the chocolate mixture on top. Use a chopstick or knife to swirl the two mixtures together.
Bake: Bake in a preheated oven at 170°C (338°F) for 30 minutes. Let cool before serving.