Step 1
Preheat the oven to 190°C (375°F) and grease an 20x20 cm (8x8 inch) square baking pan.
Step 2
In a bowl, beat together the milk, 100 g white sugar, egg, and oil. Add 125 g flour, baking powder, and salt; mix until smooth. Pour the batter into the prepared baking pan and sprinkle with mulberries.
Step 3
In another bowl, mix 90 g flour, brown sugar, and 50 g white sugar. Cut in the butter and stir until the mixture resembles crumbs, about 2 minutes. Sprinkle this crumb mixture over the cake batter.
Step 4
Bake in the preheated oven for about 30 minutes or until a toothpick inserted in the center comes out clean.