Preheat oven to 350°F. Coat 2 (10x4½-inch) loaf pans with cooking spray.
Prepare the streusel: In a medium bowl, combine streusel ingredients. Mix until a loose crumb consistency forms. Sprinkle ¼ cup crumbs into each pan. Reserve remaining streusel for the topping.
Prepare the babka batter: In a large bowl, combine eggs, sugar, and oil. Whisk until thick and light yellow in color. Add remaining babka ingredients, whisking until completely smooth.
Prepare the chocolate filling: In a medium bowl, whisk together chocolate filling ingredients until a smooth and pourable consistency has been reached.
Pour one-quarter of the babka batter over crumbs in each loaf pan. Pour one-quarter of the babka filling over the batter in each pan. Use a knife to cut through the batter and marbleize the filling. Pour remaining batter over the marbleized batter in each pan, dividing it evenly. Pour remaining babka filling evenly over the batter. Top with remaining streusel.
Place loaf pans on a metal baking sheet; bake for 60 minutes.The metal baking sheet conducts heat and ensures that the babkas bake evenly. Use a toothpick to test for doneness. A toothpick inserted in the center should come out clean.