Chocolate Chip Walnut Streusel Coffee Cake

Are you ready to make the most insane, over-the-top coffee cake in the history of ever? We're talking a super thick layer of streusel sitting boldy atop a sour cream cake swirled with a spiced cocoa and walnut mixture and dotted with chocolate bits. You'll have no less than 5 dirty bowls staring you in the face once you slide the pan in the oven, but every single one is worth it.