Red Plum Upside-Down Cake

Ingredients

• 1 Pound Dried Red Plum
• Boiling Water
• 1 Stick (4 Oz.), plus 5 tablespoons unsalted butter, softened
• 3/4 Cup Light Brown Sugar
• 1 Bourbon Madagascar Vanilla Beans , seeds scraped out
• 1/4 Teaspoon Ground Nutmeg
• 1 1/2 Cups All-Purpose Flour
• 3/4 Cup White Sugar
• 2 Teaspoons Baking Powder
• 1/2 Teaspoon Kosher Sea Salt Flakes
• 2 Large Eggs, lightly beaten
• 1/3 Cup Milk
• 1 Teaspoon Vanilla Extract, Bourbon Madagascar
• Vanilla Ice Cream, for serving