Preheat oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan.
In a medium saucepan, melt the butter over low heat. Remove from heat and stir in brown sugar until smooth.
Beat in eggs one at a time, then stir in vanilla extract.
In a separate bowl, whisk together flour, baking powder, salt, and ground cinnamon. Gradually add dry ingredients to the butter mixture, stirring until combined.
Spread batter evenly into prepared pan. Bake for 25 minutes or until a toothpick inserted in the center comes out clean.
While blondies bake, prepare cream cheese glaze by beating together cream cheese, powdered sugar, vanilla extract, and milk until smooth.
Allow blondies to cool for 15 minutes before spreading glaze evenly over the top. Let set before slicing and serving.
Notes
Store blondies in an airtight container at room temperature for up to 3 days or refrigerate for up to a week.