Plum-Nectarine Buckle

INGREDIENTS

• 6 tablespoons unsalted butter, melted
• 1 1/2 cups all-purpose flour
• 1 cup plus 2 tablespoons sugar
• 1 1/2 teaspoons baking powder
• 1/8 teaspoon ground allspice
• Salt
• 1 large egg
• 2/3 cup whole milk
• 1 teaspoon pure vanilla extract
• 3/4 pound plums, halved, pitted, and cut into 1/2-inch-thick wedges (2 cups)
• 3/4 pound nectarines, halved, pitted, and cut into 1/2-inch-thick wedges (2 cups)
• 1 tablespoon fresh lemon juice
• Crumble Topping