1-First Step: Get the oven and pans ready Start by preheating your oven to 350 degrees Fahrenheit. Line two baking sheets with parchment paper so the cookies do not stick and cleanup stays easy. This small step makes the whole process smoother once the dough is mixed.

2-Second Step: Mix the dry ingredients In a medium bowl, whisk together the all-purpose flour, Dutch process cocoa powder, salt, and baking powder. Mixing the dry ingredients first helps spread the cocoa and leavening evenly through the dough. Set the bowl aside while you work on the butter and sugar.

3-Third Step: Cream the butter and sugars In a large bowl, beat the softened unsalted butter, light brown sugar, and granulated white sugar with an electric mixer for about 2 minutes. You want the mixture to look smooth and a little fluffy. This step adds air to the dough and helps create a softer cookie.

4-Fourth Step: Add the yolks and vanilla Add the room-temperature egg yolks and vanilla bean paste or extract. Mix for 1 to 2 minutes, or until the mixture looks pale and fluffy. Room-temperature yolks blend more easily and help the dough come together with a nice light texture.

5-Fifth Step: Add the dry ingredients Gradually mix the dry ingredients into the wet mixture until just combined. Stop as soon as you no longer see dry flour. If you overmix at this stage, the cookies can turn out tougher than you want.

6-Sixth Step: Shape the dough Scoop the dough into 34 portions, about 1 tablespoon each, then roll each portion into a ball. Place the dough balls on the prepared baking sheets, leaving about 1 1/2 inches between each one. The spacing helps the cookies bake evenly.

7-Seventh Step: Make the thumbprint shape Press each dough ball with a 1/4 teaspoon to create a neat indent in the center. Using a measuring spoon instead of your thumb gives a cleaner, more even look and helps the centers stay uniform after baking.

8-Eighth Step: Chill the dough Chill the baking sheets with the shaped dough for at least 1 hour. This is one of the most important steps for Chocolate Thumbprint Cookies because it helps prevent spreading and keeps the indent from disappearing in the oven. If you are short on time, try freezing the dough balls first and then thawing them in the fridge before baking.

9-Ninth Step: Bake Bake the cookies for 9 to 11 minutes, with 10 minutes being the sweet spot for many ovens. The cookies should look set around the edges but still soft in the middle. Do not overbake if you want that chewy, melt-in-your-mouth texture.

10-Tenth Step: Re-shape the centers As soon as the cookies come out of the oven, gently press the centers again with a 1/4 teaspoon. Then use a circular cookie cutter around each cookie if needed to keep the shape tidy. This post-bake shaping trick helps your chocolate thumbprint cookies look neat and bakery-style.

11-Eleventh Step: Cool the cookies Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack. Cooling them on the sheet for a few minutes helps them firm up so they do not break when you move them.

12-Twelfth Step: Make the ganache For the filling, heat the heavy whipping cream until it is just about boiling. Pour it over the semi-sweet chocolate chips and let it sit for 1 minute. Stir until the mixture is smooth and glossy. If you want to use chopped chocolate bars instead of chips, that works too.

13-Thirteenth Step: Fill the cookies Spoon about 1 teaspoon of ganache into each center. Add the filling after the cookies have cooled enough to hold their shape, but do not wait too long if you want the ganache to settle nicely in the wells.

14-Fourteenth Step: Decorate and set Top with nonpareils if you want a festive finish. You can also use crushed candy canes for a holiday look. Chill the cookies for 10 to 15 minutes so the ganache sets. After that, they are ready to serve.