Prepare the cinnamon cookies:

1. In a medium to large sized mixing bowl, whisk together the flour, cinnamon, baking soda, baking powder, and salt, until well-combined. Set aside.
2. In a large mixing bowl, whisk together the melted butter, brown sugar, white sugar, egg, and vanilla, until very smooth and well-combined.
3. Add the dry mixture into the wet, then stir together until fully-combined. Set aside while you make the streusel.

Make the streusel topping:

1. In a medium mixing bowl, whisk together the flour, brown sugar, white sugar, cinnamon, and pinch of salt, then drizzle in the melted butter. Mix together until it resembles wet sand.

Assemble and glaze:

1. Prepare a large baking sheet with parchment paper.
2. Using a medium cookie scoop, scoop out the cinnamon cookies, then place onto the prepared baking sheet. Use your hands to slightly flatten the cookies,
3. Press a heaping amount of streusel on top of each cookie.
4. After all of the cookies have been assembled, place them into the freezer for 20 minutes.
5. Preheat the oven to 375F. Prepare another baking sheet with parchment.
6. Place 6 cookies onto the baking sheet. Place into the oven to bake for 12-13 minutes. Repeat baking with remaining cookies, then allow cookies to cool completely on a wire rack before glazing.
7. In a small mixing bowl, whisk together the confectioners’ sugar and milk until smooth. Use a spoon to drizzle the glaze over the cooled cookies. Allow glaze to set before enjoying.