Bronwen Wyatt's Upside Down Cake - California Prunes

Ingredients

• ½ cup light brown sugar
• 4 TBSP butter
• 2 TBSP good-quality vinegar (such as apple cider or rosé vinegar)
• Zest of 1 orange
• 1 tsp vanilla extract
• ½ tsp salt
• 2 TBSP sesame seeds
• 2 cups prunes (sliced longways in three)
• 12 TBSP butter
• 1 cup packed light brown sugar
• 2 eggs (room temp)
• Zest and juice of 1 orange
• 2 TBSP extra virgin olive oil
• 1 tsp good-quality vinegar (such as apple cider or rosé vinegar)
• 1 ¾ cup all-purpose flour
• ¾ tsp salt
• ½ tsp baking soda (bicarb)
• ¼ tsp baking powder