Generously butter a 10" tube pan. Roll the dough to a 12"x 16"rectangle. Brush the surface of the dough with egg wash. Sprinkle the streusel over the dough. Roll the dough into a log, pinch the seam to seal.
Bring the two ends of the log together to form a ring. Pinch the ends together.
Transfer the dough to the prepared baking pan. Cover the pan and place the cake in the refrigerator overnight.
The next morning, take the cake out of the refrigerator. The cake should rise in the refrigerator overnight, but it is probably not fully proofed. It should be almost doubled in volume. Leave the cake at room temperature to finish rising, it may take 1-1.5 hours.
Meanwhile, preheat the oven to 350 °F. To speed up the rising you can put the pan in the oven, VERY BRIEFLY, while it's just starting to warm up.
Brush the surface of the cake with egg wash. Grab large chunks of the crumb topping and break them into smaller chunks over the surface of the cake.
Bake until the cake is well risen and golden brown, about 30 minutes. You can use a probe thermometer to check the internal temperature. It should be about 200 °F.
Cool the cake for 20 minutes in the pan, then turn out onto a cooling rack to cool completely.
Combine 4 oz confectioner's sugar with 1 oz whole milk and 1 teaspoon vanilla extract to form an icing with the texture of thin pancake batter. Drizzle the glaze over the cake and allow it to set.