• Preheat the oven to 400˚F (200˚C) and grease an 8 inch (20 centimeter) square baking pan.
• In a large mixing bowl, add the sugar, eggs, vanilla and apricot jam and whisk together using an electric hand mixer until the mixture turns pale, thick and glossy.
• In a separate bowl, sift the flour and add the baking soda and salt.
• Add a little of the milk slowly into the egg mixture while whisking. Then add some of the flour.
• Alternate the two until all the milk and flour are incorporated into the batter.
• Then add the melted butter and finally the vinegar, giving it a final whisk to combine.
• Pour the batter into the pan and bake for 30-40 minutes until set and the top is a dark brown color.

While the cake is baking, make the caramel sauce:

• Put the sugar in a saucepan. Place the pan over low heat and gently cook until the sugar starts melting around the edges.
• Start shaking the pan to move the dry sugar into the wet patches and keep shaking until the sugar is evenly melted and starts to caramelize. Do not be tempted to stir with a spoon or it may crystallize and you will have to start again.
• When the caramel is a dark golden brown and before it burns, add the butter carefully, as it may sputter, and stir until melted and well mixed in.
• In another small pot over low heat, warm the cream for a few minutes until bubbles start forming around the edge, then pour into the caramel.
• Add the vanilla and 3 1/2 tablespoons of water.
• Keeping the heat low, cook the caramel sauce for 3-5 minutes until it is smooth.
• As soon as the cake is out of the oven, use a fork to poke holes all over the top.
• Pour half of the caramel sauce over it and let it absorb for at least 15-20 minutes.
• Cut into squares and serve with ice cream and the rest of the warm caramel sauce on the side.