In a mixing bowl, combine cold butter cubes, flour, brown sugar, ground cinnamon, and a pinch of salt. Work the mixture until it resembles coarse crumbs. Transfer to the refrigerator to chill.

In a separate bowl, sift together the all-purpose flour, baking soda, ground cinnamon, and salt. Set aside.

In a large mixing bowl, beat the softened unsalted butter, granulated sugar, and brown sugar for 2 to 3 minutes until light and fluffy.

Add the large eggs one at a time, mixing thoroughly after each addition, then stir in the vanilla extract. Beat until smooth.

Gradually mix the dry ingredients into the wet ingredients using a spatula until just combined.

Scoop dough and place onto parchment-lined baking sheets, leaving space between each.

Indent the center of each dough ball gently, cover with plastic wrap, and refrigerate for 1 to 2 hours.

Preheat the oven to 350°F (175°C). Arrange the chilled cookies on baking sheets, sprinkle with streusel topping, and bake for 13 to 15 minutes.

Allow cookies to cool completely, then whisk together powdered sugar, whole milk, and vanilla extract for icing. Drizzle over cookies and let set.