- Butter a 6-inch (15 cm) springform pan with removable bottom.
- In a pot, bring the water and dates to a boil. Add the baking soda and mix well. Remove from the heat and let cool.
- In a bowl, combine the flour and baking powder.
- In another bowl, cream the butter and brown sugar with an electric mixer. Add the egg and whisk until smooth. With the machine running on low speed, whisk in the dry ingredients alternating with the milk and the date mixture. Pour the batter into the springform pan.
- Prepare a hot water bath in the pressure cooker: place a silicone rack at the bottom of the pressure cooker and add 1 ½ cups (375 ml) of water. Place the cake pan on the roasting rack (see note).
- Cover and select the Programmable function on HI (highpressurization). Set the machine to cook for 25 minutes.
- Meanwhile, in a small pot, bring the cream and brown sugar to a boil. Simmer for 2 minutes. Set aside.
- Let the pressure release naturally (about 15 minutes). Once the pressure is released, remove the lid.
- Remove the cake from the pressure cooker. Prick the top of the cake all over with a toothpick. Pour the caramel sauce over the cake. Let cool before unmoulding. Serve warm or cold.
If you do not have a silicone rack, make a log of foil about 18 inches (45 cm) long and place at the bottom of the pressure cooker. The cake pan should not touch the water and should be sitting flat on the foil log.