Summer Sweets: Peach-Blackberry Crumble

Ingredients

• 5 cups sliced skin-on peaches (about 5 large, ripe peaches)
• 2 pints fresh blackberries
• 1/4 cup all-purpose flour
• 1/4 cup granulated sugar
• 1 teaspoon cornstarch
• 1 teaspoon pure vanilla extract
• 1 teaspoon grated lemon zest and freshly squeezed lemon juice
• 1 cup all-purpose flour
• 1/2 cup old-fashioned rolled oats (not quick-cooking)
• 1/4 cup, plus 2 tablespoons packed light brown sugar
• 1/2 teaspoon fine sea salt
• 1/2 teaspoon ground cinnamon
• 1/2 cup (1 stick) unsalted butter
• 1/2 cup chopped pecans
• vanilla ice cream