Add the jaggery powder to the warm milk and stir for 3 to 4 minutes until it melts completely. If there are lumps, warm gently on low heat without boiling. Cool for 5 minutes.
Preheat the oven to 175°C (347°F). Grease a 7-inch tin and line it with parchment paper.
To the jaggery milk, add the oil, eggs and vanilla. Whisk well until smooth and slightly frothy.
Sift in the flour, baking powder, baking soda, cardamom, ginger and salt. Fold gently until just combined. The batter will be thin, and that's normal.
Pour the batter into the tin, tap on the counter to remove air bubbles, and scatter the nuts and raisins on top.
Bake for 35 to 40 minutes, until a toothpick comes out clean. Start checking at 30 minutes.
Rest in the tin for 10 minutes, then lift out and cool completely on a wire rack before cutting.