Blackberry Big Crumb Coffee Cake

Ingredients (23)

• For Filling:
• 1 pint blackberries, washed and halved
• 1/4 cup sugar
• 1 tablespoon corn starch
• For the Big Crumbs:
• 1/3 cup brown sugar
• 1/3 cup sugar
• 1 teaspoon cinnamon
• 1 teaspoon crystallized ginger, mashed
• 1/2 cup unsalted butter, melted
• 1 3/4 cups cake flour
• A pinch of salt
• Cake:
• 1/3 cup sour cream
• 1 large egg
• 1 large egg yolk
• 2 teaspoons vanilla extract
• 1 cup cake flour
• 1/2 cup sugar
• 1/2 teaspoon baking powder
• 1/2 teaspoon baking soda
• 1/4 teaspoon salt
• 6 tablespoons butter, cut into pieces and softened