In a medium saucepan, melt ¾ cup butter over medium heat. Stir frequently as it foams and the milk solids begin to separate and sink. Continue stirring until the butter turns golden brown, smells nutty, and you hear light crackling—about 5–7 minutes.
¾ cup unsalted butter
Pour the browned butter into a heat-safe bowl and let it cool completely to room temperature.
While it cools, reuse the same saucepan to brown the butter for the cookie dough.
Make the Cookie Dough:
Add ¾ cup unsalted butter to the saucepan. Brown it the same way: stirring constantly over medium heat until it’s golden, aromatic, and the bottom has browned bits—about 5–7 minutes.
¾ cup unsalted butter
Immediately pour the butter (including brown bits) into a large mixing bowl and let it cool for 10–15 minutes, until warm but not hot.
Preheat oven to 350°F. Line two baking sheets with parchment paper.
Add the granulated sugar and brown sugar to the bowl with the browned butter. Whisk until the mixture is shiny and smooth—about 1 minute.
1 cup granulated sugar, ½ cup light brown sugar
Add the chilled egg, egg yolk, and vanilla. Whisk vigorously until lightened in color and slightly thickened. It should almost double in volume.
1 large egg, 1 large egg yolk, 1 teaspoon vanilla extract
Sprinkle in the cornstarch, baking soda, cream of tartar, salt, cinnamon, and flour. Switch to a rubber spatula and fold the dough until no flour streaks remain.
1 teaspoon cornstarch, 1 teaspoon baking soda, 1 teaspoon ground cinnamon, ½ teaspoon cream of tartar, ½ teaspoon salt, 2 ½ cups all-purpose flour
In a small bowl, mix ⅓ cup granulated sugar with 1 teaspoon cinnamon for rolling.
Using a 2-tablespoon scoop, portion out dough and roll each ball in the cinnamon sugar. Place 12 dough balls per tray.
Bake for 8 minutes. Remove from the oven and gently flatten the tops with a flat spatula while still hot. Let cookies cool completely on a wire rack.
Make the Frosting:
Once the browned butter has cooled to room temperature, add it to a large bowl with the cream cheese. Beat with a hand mixer on medium speed for 2–4 minutes until light and fluffy.
4 oz cream cheese
Add powdered sugar, vanilla, heavy cream, and salt. Mix on low until just combined, then increase speed and beat for 2 more minutes.
3 cups powdered sugar, 1 teaspoon heavy whipping cream, ½ teaspoon vanilla extract, Pinch of salt
Use a rubber spatula to smooth out any air bubbles in the frosting.
Assemble:
Spread or pipe the frosting onto the bottom side of half the cookies. If piping, Wilton tip #1M works great for an even swirl.
Top with remaining cookies and press gently to sandwich them together.