Preheat the oven to 350 degrees. Grease a 9" X 13" baking pan.
In a bowl, combine softened butter, softened cream cheese, and sugar. Beat until smooth. Add eggs and vanilla and mix well.
Sift together the dry ingredients: flour, baking soda, and salt. Add 1/2 of the dry ingredients to the cream cheese mixture, and stir until just combined. Pour in the milk and mix again. Add the other 1/2 of the dry ingredients and stir until just combined.
Transfer the batter to the prepared baking dish. Evenly sprinkle the topping and chopped macadamia nuts over the batter.
Bake for 25 minutes or until a toothpick in the center comes out clean. Let the cake cool for about 15 minutes then cut into slices and serve.
Topping
Combine the flour, brown sugar, and cinnamon together in a medium bowl. Cut in the chilled butter with a pastry cutter, forks, or your hands into pea-sized crumbles.
Notes
Note: The cake may also be baked in two 9" round cake pans.Storage: Store for 2 days in an air-tight container or up to 1 week in an air-tight container in the fridge.