Position an oven rack in the center and another on the bottom. Preheat the oven to 325°F.

In a medium bowl, mix together graham cracker crust ingredients until well combined. Pack the mixture into the bottom and halfway up the sides of a 9-inch springform pan. Bake for 8 minutes.

For the cinnamon swirl, mix together all the ingredients in a small bowl, and set aside.

For the streusel topping, mix and mash together all of the ingredients in a medium bowl until well moistened and crumbly. Set aside.

In a large bowl, combine cream cheese and sugar. Beat together until smooth.

Add sour cream, flour, salt, and vanilla extract to the cream cheese mixture. Mix until combined.

Add eggs one at a time, mixing after each addition until incorporated.

Pour half of the cheesecake filling over the cooled crust. Sprinkle the cinnamon swirl filling over top. Drizzle remaining cheesecake filling on top and swirl gently with a skewer.

Sprinkle the streusel evenly over top.

Fill a large pan with 2 cups of boiling water and place it on the bottom rack of your preheated oven. Place the cheesecake on the center rack.

Bake for 70 minutes, then remove the water pan and continue baking for another 20 to 30 minutes until slightly puffed and jiggles in the center.

Cool in the oven for 2 hours with the door slightly ajar. Run a thin knife along the edges after 30 minutes.

Cool to room temperature, then chill for at least 4 hours or until fully set.

For the icing, whisk together powdered sugar and 1 tablespoon of milk. Adjust with more milk as needed for desired consistency.

Remove the cheesecake from the pan and drizzle icing over top before serving.