Cream the 8 tbsp butter, 4 oz cream cheese, and 1 cup sugar with an electric mixer on medium until light and fluffy, about 2 minutes. Beat in the egg and 2 tsp vanilla.

Whisk the 2 cups flour, 1/2 tsp baking powder, and 1/4 tsp salt in a separate bowl. With the mixer on low, gradually add the dry mix to the wet, stopping as soon as the flour disappears.

Turn the dough onto a lightly floured parchment sheet and pat into a 10x8-inch rectangle. Brush with the 3 tbsp melted butter. Stir the 1/4 cup brown sugar, 1 tbsp flour, and 2 tsp cinnamon together; sprinkle evenly over the butter. Roll the dough tightly into a log, wrap in the parchment, and freeze for 10 minutes if soft.

Heat oven to 350°F (175°C). Line a baking sheet with parchment. Slice the log into 1/2-inch rounds with a serrated knife and place them 2 inches apart on the sheet.

Bake for 10 to 12 minutes, until the edges are just golden and the centers look set. Cool on the sheet for 2 minutes, then transfer to a wire rack to cool completely.