In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.

In a large bowl with an electric mixer (stand mixer or hand mixer), cream together the softened unsalted butter and granulated sugar until light and fluffy, about 2-3 minutes. Beat in the egg until fully incorporated, then stir in the vanilla extract.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined and a soft dough forms. Do not overmix.

Lightly flour a clean surface or a large piece of parchment paper. Roll the cookie dough into a large rectangle, approximately 12x16 inches and about 1/4 inch thick.

In a small bowl, combine the melted butter, light brown sugar, and ground cinnamon for the filling. Mix until a thick paste forms. Evenly spread the cinnamon filling over the rolled-out dough, leaving a small border (about 1/2 inch) on one of the longer edges.

Starting from the long edge *opposite* the un-filled border, carefully and tightly roll the dough into a log. Once rolled, gently press the seams to seal. Wrap the log tightly in plastic wrap and chill in the refrigerator for at least 30 minutes (or up to 2 hours) to firm up, which makes slicing easier.

Preheat your oven to 375°F (190°C). Line two baking sheets with parchment paper.

Remove the chilled dough log from the refrigerator. Using a sharp knife, slice the log into 1/2-inch thick rounds. Place the cookie slices about 2 inches apart on the prepared baking sheets.

Bake for 10-12 minutes, or until the edges are lightly golden and the centers are set. The centers may still look a little soft, which is perfect for a chewy cookie. Let the cookies cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.

While the cookies are cooling, prepare the glaze. In a medium bowl, beat together the softened cream cheese and softened unsalted butter until smooth and creamy.

Gradually add the powdered sugar, mixing until well combined. Stir in 2 tablespoons of milk and the vanilla extract. If the glaze is too thick, add the remaining tablespoon of milk, a teaspoon at a time, until you reach a smooth, pourable consistency.

Once the cookies are slightly warm or completely cooled, generously drizzle the cream cheese glaze over them. Allow the glaze to set for a few minutes before serving.