Step 1

Make the dough: Arrange 2 racks to divide the oven into thirds and heat the oven to 350°F. Line 3 baking sheets (or as many as you have) with parchment paper or silicone baking mats.

Step 2

Place 2 sticks unsalted butter in a large microwave-safe bowl and microwave in 20-second bursts until fully melted, 60 to 70 seconds total. (Alternatively, melt on the stovetop and transfer to a large bowl.)

Step 3

Place 2 3/4 cups all-purpose flour, 1 teaspoon ground cinnamon, 3/4 teaspoon kosher salt, 1/2 teaspoon baking powder, and 1/2 teaspoon baking soda in a medium bowl and whisk until combined.

Step 4

Add 1 cup granulated sugar, 3/4 cup packed brown sugar, 1 large egg, 1 large egg yolk (reserve the white for the streusel coating), and 1 tablespoon vanilla extract to the melted butter. Whisk until smooth and glossy. Add the flour mixture and stir with a rubber spatula or wooden spoon just until the flour is incorporated and a smooth dough forms.

Step 5

Make the streusel coating: Place 4 tablespoons unsalted butter in a medium microwave-safe bowl and microwave 10-second bursts until fully melted, 30 to 40 seconds. (Alternatively, melt on the stovetop and transfer to a medium bowl.) Add 1/2 cup all-purpose flour, 1/2 cup packed brown sugar, 1/2 cup granulated sugar, 2 teaspoons ground cinnamon, and 1/4 teaspoon kosher salt. Using your fingertips, pinch and squeeze the dry ingredients into the melted butter until large, irregular clumps form and the mixture resembles wet sand. Whisk 2 large egg whites in a medium bowl until frothy.

Step 6

Scoop out the dough with a #24/2-inch wide cookie scoop, or portion into 18 (about 3 scant tablespoon) portions, and roll into balls. (If the dough is too soft to roll into balls, let it sit for 10 minutes and try again.)

Step 7

Working with 1 dough ball at a time, roll in the egg whites allowing the excess to drip off, then transfer it into the streusel. Toss until completely coated in streusel, using your hands to gently press the streusel into the dough to help it stick. (Make sure to use one hand for tossing the dough balls in the egg whites and one for tossing in the streusel to prevent the streusel from getting wet.) Place at least 2 inches apart on the baking sheets, 6 per sheet. Top the cookie dough balls with the remaining streusel, mounding it at the top of the cookie dough balls.

Step 8

Bake the first 2 sheets for 8 minutes. Rotate the baking sheets from front to back and top to bottom and bake until cracks start forming, 7 to 10 minutes more. Let cool slightly on the baking sheets for 5 minutes, then transfer onto a wire rack to cool completely, about 30 minutes.

Step 9

Bake the final batch on the upper rack, rotating it front to back halfway through baking, 15 to 18 minutes total. (If reusing a baking sheet to bake this batch, let it cool for 15 minutes first.) a

Step 10

Make the icing: Place 1 cup powdered sugar and 2 tablespoons milk in a small bowl and whisk until the powdered sugar is completely dissolved. The glaze should be thick yet pourable. If too thin, whisk in more powdered sugar 1 tablespoon at a time. If too thick, whisk in more milk 1 teaspoon at a time. Drizzle the icing over the cookies in a zig-zag pattern and let sit for 10 minutes for the icing to set before serving.