1-First Step: Mix the dry ingredients In a medium bowl, whisk together 1 1/2 cups all-purpose flour and 1/2 teaspoon baking soda. This first step spreads the leavening evenly through the flour, which helps the cookies bake with a balanced texture. Set the bowl aside while you work on the wet mixture. For the best texture, whisk just until the ingredients look even. If you want smoother mixing later, you can sift the flour first, but it is not required. Keep the bowl nearby so you can add it later without overworking the dough.

2-Second Step: Build the matcha base In a large bowl, mix 1 1/2 tablespoons matcha powder and 1 1/2 tablespoons pure vanilla extract into a paste. This step helps break up any matcha clumps and gives the dough a smoother color and flavor. Then add 1/2 cup unsalted butter at room temperature, 1 tablespoon creamy peanut butter, 3/4 cup granulated sugar, 1/4 cup packed light brown sugar, and 1/2 teaspoon coarse kosher salt. Beat the mixture until it looks fluffy and well blended. The butter should be soft enough to cream easily, and the sugar should start to dissolve into the fat. This creates the base for a tender cookie with a nice chewy center.

3-Third Step: Add the egg Whisk in 1 large egg at room temperature until smooth. Room-temperature eggs blend more easily into the butter mixture, which helps the dough stay even. If the egg is cold, the dough may look slightly curdled at first, so let it sit out beforehand if you can. At this stage, the dough should look glossy and thick. Scrape down the sides of the bowl so every bit of matcha, sugar, and butter gets mixed in.

4-Fourth Step: Add the dry mixture Add the flour mixture to the wet ingredients and fold until combined. Mix only until you no longer see dry flour. Overmixing can make the cookies tougher, so stop as soon as the dough comes together. The dough will be soft, and that is normal. Matcha cookie dough benefits from a short chill because it helps the butter firm up and keeps the cookies from spreading too much in the oven.

5-Fifth Step: Chill the dough Refrigerate the dough uncovered. This short chill helps the flavors settle and improves the final shape. If your kitchen is warm, a brief chill becomes even more important because soft dough can spread too quickly. You do not need a long rest, but even a short time in the fridge makes the cookies easier to scoop. The dough should feel firmer before it goes onto the baking sheet.

6-Sixth Step: Prepare the oven and baking sheets Heat the oven to 350 degrees Fahrenheit and line baking sheets with parchment paper. Parchment helps the cookies bake evenly and makes cleanup easier. It also keeps the bottoms from browning too fast. Make sure the oven is fully heated before the cookies go in. Starting with a hot oven helps the cookies puff properly and gives them a better shape.

7-Seventh Step: Scoop and bake Scoop 1 1/2-inch rounds onto the prepared sheets. Leave a little space between each cookie so they can spread without touching. Bake for about 12 minutes, or until the cookies look puffed and set around the edges. The centers may look a little soft when they come out, but that is fine. They will keep cooking on the hot pan after baking. If you want extra uniform cookies, use a cookie scoop for even portions.

8-Eighth Step: Cool the cookies Cool the cookies on the pan before moving them. This resting time helps them finish setting without breaking apart. Once they are cool enough to handle, transfer them to a rack if needed. If you plan to frost them, make sure they are fully cool first. Warm cookies can melt the frosting and make it slide off.

9-Ninth Step: Make the optional frosting For the frosting, whisk 3/4 cup granulated sugar, 3 tablespoons all-purpose flour, and a small pinch of coarse kosher salt with 1 cup whole milk in a saucepan. Cook over medium heat until the mixture bubbles and thickens. Stir often so the bottom does not scorch. Once it is thick, transfer the mixture to a mixer and beat until cool. This cooling step matters because warm frosting will not whip properly. Then add 1 cup unsalted butter at room temperature gradually and beat until fluffy.

10-Final Step: Frost and finish Spread the frosting over the cooled cookies and add nonpareil sprinkles if desired. If you prefer a simpler finish, skip the frosting and dust the cookies with powdered sugar instead. Either way, the cookies are ready to serve once the topping is set.