Place the apricots, vanilla bean and water in a small saucepan and bring to a boil. Continue to boil until most of the water has evaporated, about 10 minutes but watch carefully during the last few minutes to make sure the pan does not boil dry. Take off the heat and let cool in the pan.
Preheat the oven to 325 degrees and spray an 8-inch springform pan with cooking spray. Line the bottom with parchment paper and spray the paper.
Reserve 8 of the apricots. Place the rest of the apricots, along with whatever water is still in the pan into a food processor. Remove the vanilla bean from the pan, cut the bean and scrape the seeds into the food processor (save the pod or another use). Add the almond flour, allulose, eggs, lemon juice, baking soda, and salt to the processor and process until smooth.
Pour the batter into the prepared pan. Split the reserved apricots into two halves and place on top of the batter. Bake for 40 minutes, lower the oven temperature to 300, and bake for another 10 minutes or until a toothpick inserted into the cake comes out clean and the cake is golden brown.
Melt the jam and brush on the top of the cake while it is still warm and let the cake cool in the pan.