Cinnamon Streusel Coffee Cake

Ingredients

• 1 3/4 cups all-purpose flour
• 3/4 cup packed light brown sugar
• 1 teaspoon ground cinnamon
• 1 teaspoon coarse salt
• 1 stick butter
• 1 cup brown sugar
• 1 1/2 tablespoons ground cinnamon
• 1 teaspoon unsweetened cocoa powder
• 1 stick unsalted butter
• 2 cups all-purpose flour
• 1 teaspoon baking powder
• 1 1/4 teaspoon baking soda
• coarse salt
• 1 cup granulated sugar
• 2 large eggs
• 1 1/2 teaspoons pure vanilla extract
• 1 cup sour cream