Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy (about 3-4 minutes).

Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking powder, baking soda, salt, and ground cinnamon.

Gradually add the dry ingredients to the wet mixture, alternating with the sour cream, mixing until just combined. Fold in the chopped nuts if using.

Drop rounded tablespoons of dough onto the prepared baking sheet, spacing them about 2 inches apart.

Bake for 10-12 minutes, or until the edges are lightly golden. Let cool on the baking sheet for 5 minutes before transferring to a wire rack.

For the glaze, whisk together the powdered sugar and milk until smooth and drizzle over the cooled cookies.