Preheat your oven to 350°F (175°C) and line a 9x13 inch baking pan with parchment paper.
Whisk together the all-purpose flour, granulated sugar, and salt in a large mixing bowl.
Add the softened unsalted butter, large egg, and vanilla extract to the flour mixture and combine until a soft dough forms.
Press about two-thirds of the dough into the bottom of the prepared baking pan and refrigerate for about 15 minutes.
Mix the very soft unsalted butter, packed brown sugar, ground cinnamon, and all-purpose flour until a thick paste forms.
Spread the cinnamon filling evenly over the chilled base layer.
Crumble the remaining dough over the cinnamon filling to create a streusel-like topping.
Bake for about 25-30 minutes, or until the top is golden brown and a toothpick inserted comes out clean.
Allow the bars to cool completely in the pan for about 30-40 minutes.
Prepare the cream cheese frosting by beating together the softened cream cheese and unsalted butter until smooth and fluffy.
Gradually add the powdered sugar, vanilla extract, and a pinch of salt, mixing until light and fluffy.
Spread the cream cheese frosting generously over the cooled bars.
Slice into squares and enjoy!