Slow Cooker Cherry Cobbler

Ingredients

• 4 cups pitted cherries
• ½ cup sugar
• 3 tablespoons cornstarch
• 1 teaspoon vanilla extract
• 2¼ cups all-purpose flour
• ⅓ brown sugar
• 1¼ teaspoons baking powder
• ½ teaspoon baking soda
• pinch of salt
• 6 tablespoons unsalted butter, melted
• ⅔ cup buttermilk
• 1 egg, beaten
• Vanilla ice cream, for serving (optional)