Preheat the oven to 180°C (350°F). Line an 8-inch round springform pan with baking paper and lightly grease the base and sides.

In a large mixing bowl, combine the flour, brown sugar, egg, milk, melted butter, and vanilla extract. Beat thoroughly until the mixture is smooth and airy.

In a separate bowl, prepare the crumble by combining the flour, brown sugar, cinnamon, and softened butter. Rub gently with your fingertips until the texture resembles coarse breadcrumbs.

Transfer the cake batter into the prepared tin, spreading it evenly. Distribute most of the mulberries across the surface, setting a few aside for garnish. Layer the crumble mixture over the top.

Place the tin in the preheated oven and bake for about 35 minutes or until the top is golden and the cake is baked through.

Serve warm, optionally dusted with icing sugar, garnished with the reserved mulberries, and accompanied by fresh cream or a scoop of ice cream.