Warm Strawberry Crumb Cake

INGREDIENTS

• 3 pounds strawberries, hulled and halved (8 cups)
• 1/2 cup sugar
• 2 tablespoons freshly squeezed lemon juice
• 2 1/2 tablespoons cornstarch dissolved in 2 1/2 tablespoons of water
• 1 vanilla bean, split and seeds scraped
• 1/2 cup lightly packed light brown sugar
• 1/2 cup plus 2 tablespoons all-purpose flour
• pinch of salt
• 4 tablespoons unsalted butter, cubed and chilled
• 2 1/4 cups all-purpose flour
• 1 tablespoon baking powder
• 3/4 teaspoon salt
• 1 stick unsalted butter, softened
• 1 1/4 cups sugar
• 3 large eggs
• 1 1/2 teaspoons pure vanilla extract
• 3/4 cup buttermilk