Pre-heat oven to 190°C (170°C fan-forced). Line a 22 x 30cm slice tray with baking paper, extending beyond the tray.
For the sponge, place eggs into the bowl of an electric mixer and beat for 2-3 minutes. Add sugar gradually until all combined. Continue beating until mixture has thickened.
On a gentle speed, fold in the sifted flour, cocoa, spice and baking powder, whilst pouring the milk down the side of the bowl. Mix until all ingredients are just combined.
Pour batter into the prepared tray and gently spread out if required. Bake for 12 minutes, or until the sponge springs back when lightly pressed. Remove from the oven and turn out onto a clean tea towel. Peel away the paper that the sponge was cooked in and roll the sponge from the short edge into a roll. Set aside to cool.
Prior to serving, place chocolate and cream in a heatproof bowl over a saucepan of gently simmering water. Stir until melted.
To serve, unroll the sponge gently and spread with half of the whipped cream, sprinkle with the diced strawberries, then roll back up to enclose the filling. Place onto a serving plate and drizzle with the melted chocolate. Finish with dollops of the remaining cream, additional strawberries and raspberries.