1-First Step: Mix the dry ingredients In a medium bowl, whisk together the all-purpose flour and baking soda until they are fully blended. This step helps the leavening spread evenly through the dough, so the cookies bake up with a consistent texture. If you are using a gluten-free blend, whisk it the same way so the starches are evenly mixed before you combine everything.

2-Second Step: Build the flavor base In a large bowl, stir the matcha powder and pure vanilla extract into a paste. This simple move helps break up the matcha before it goes into the dough, which can reduce clumps and give the cookies a smoother green color. Add the room-temperature butter, creamy peanut butter, granulated sugar, light brown sugar, and coarse kosher salt, then beat until the mixture looks pale and fluffy. That usually takes a few minutes, and it is worth the time because good creaming gives the cookies a softer crumb.

3-Third Step: Add the egg and finish the dough Whisk in the egg until the mixture looks smooth and well combined. The dough should feel creamy, not greasy or separated. Then fold in the flour mixture just until you no longer see dry streaks. Stop mixing as soon as the dough comes together, since overmixing can make the cookies dense instead of tender.

4-Fourth Step: Chill the dough while the oven heats Refrigerate the dough while you preheat the oven to 350°F. Chilling helps the dough firm up, which makes scooping easier and helps the cookies keep their shape during baking. If your kitchen is warm, even a short chill can make a big difference in how the cookies spread.

5-Fifth Step: Scoop and bake Line baking sheets with parchment paper. Scoop 1 and 1/2-inch rounds of dough onto the sheets, leaving space between each one so the cookies can puff without running into each other. Bake for about 12 minutes, or until the cookies look puffed and no longer wet on top. The centers should still look soft, which helps them stay chewy after cooling.

6-Sixth Step: Let the cookies cool on the pan Leave the cookies on the baking sheet until they cool completely. This matters because the cookies deflate a little and become chewier as they cool, which gives them a better bite. If you move them too soon, they may break or lose that soft middle texture.

7-Seventh Step: Make the vanilla frosting For the frosting, combine the granulated sugar, all-purpose flour, small pinch of coarse kosher salt, and whole milk in a saucepan. Whisk until smooth, then cook over medium heat while whisking constantly. The mixture will bubble and thicken like pudding. When it reaches that texture, transfer it to a mixer bowl and beat on high speed until it cools down. Gradually add the room-temperature butter and beat until fluffy, then mix in the vanilla extract.

8-Eighth Step: Frost and finish Spread or pipe the frosting onto the cooled cookies. Add nonpareil sprinkles if you want a more festive look. The frosting brings a creamy sweetness that works well with the earthy matcha and nutty peanut butter. If you prefer a simpler finish, you can skip the frosting and dust the cookies lightly with powdered sugar instead.