To make the crust, combine the graham cracker crumbs and sugar, then add melted butter, mixing with a fork.
Press into bottom and slightly up sides of a 9 inch spring-form pan and bake in the oven for about 8 minutes to set it.
Next start to make the streusel. In a large bowl, mix together the graham cracker crumbs, brown sugar, and cinnamon, then add your melted butter and stir thoroughly.
In a medium sized bowl mix together the cream cheese and sugar. Add the vanilla, then add eggs one at a time, beating well after each egg. Make sure you scrape the sides of the bowl with a spoon or rubber spatula to fully mix all of the ingredients.
Pour half of the cheesecake mixture onto the crust, then top with half of the streusel.
Pour the remaining cheesecake batter on top, then add another layer with the remaining streusel.
Place spring-form pan on baking sheet and place in the middle rack of the oven. Bake about 50-60 minutes.
Allow to cool fully in fridge before topping.
For the topping, mix together the melted butter, vanilla and powdered sugar. Add small amounts of milk to thin, if needed. Place topping into a piping bag (or ziploc bag with a small corner cut out.) Drizzle/pipe over cheesecake in a criss-cross pattern before serving.
Variations:Add a 1/2 cup of chopped/crushed pecans to the streusel mixture for added flavor. Your favorite cream-cheese frosting can be substituted in place of the topping.