Butterbeer

Ingredients

• 1/2 stick unsalted butter, plus 1 tablespoon, divided
• 1/2 cup dark brown sugar
• 1 1/2 cup heavy cream, divided
• 1/2 teaspoon flaky sea salt
• 1.5 teaspoons vanilla extract
• 1 teaspoon grated fresh ginger
• a heaping 1/8 teaspoon fresh nutmeg
• 1.5 tablespoons light brown sugar
• 1/3 a vanilla bean
• up to 1 ounce dark rum (it will boozy)
• 1.5 cups ginger beer (or pear apple cider, or nut brown ale)
• grated nutmeg, to garnish