Slow-Cooker Peach Crumble

Ingredients

• 1 tablespoon butter, softened
• 6 large ripe peaches, peeled and sliced (about 6 cups)
• 2 tablespoons light brown sugar
• 1 tablespoon lemon juice
• 1 tablespoon vanilla extract
• 2 tablespoons coconut rum, optional
• TOPPING:
• 1 cup all-purpose flour
• 3/4 cup packed light brown sugar
• 1-1/2 teaspoons baking powder
• 1 teaspoon ground cinnamon
• 1/2 teaspoon baking soda
• 1/8 teaspoon salt
• 1 cup old-fashioned oats
• 6 tablespoons cold butter, cubed
• Whipped cream, optional