Heat the oven to 180C/160C fan/gas 4. Butter a deep 23cm square cake tin (or use a roughly 20 x 28cm rectangular tin) and line with baking parchment. Put the dates in a medium pan with the coffee, milk and bicarb, and simmer over a medium-low heat for 5-7 mins until the dates have mostly broken down.

Beat the butter and sugar together in a stand mixer or using an electric whisk. Sift in the flour, spice and xanthan gum (if using), then add the eggs. Beat until just combined, then add the date mixture and mix again. Pour the batter into the tin and bake for 40 mins until risen, firm and a skewer inserted into the middle comes out clean.

While the sponge bakes, make the sauce. Tip 150ml of the cream into a saucepan with the remaining ingredients, and warm over a low-medium heat until the butter has melted. Simmer for 4-5 mins to thicken. Remove from the heat, then stir in the remaining cream. Cut the sponge into squares or rectangles, and serve warm topped with the sauce and ice cream or cream. Once cool, the sponge will keep in an airtight tin for three days or frozen for three months (without the sauce). The sauce will keep chilled for a week or frozen for three months. Defrost the sauce in the fridge overnight, and the sponge at room temp. To reheat, cover the sponge with foil and bake for 20-30 mins at 180C/160C fan/gas 4. Warm the sauce gently in a pan. Or, microwave individual servings in heatproof bowls on high for 1 min until the sauce has melted and the sponge is hot through.