Step 1: Preheat the Oven and Prepare Baking Sheets

1. Preheat your oven to 350°F (175°C).
2. Line two baking sheets with parchment paper or silicone baking mats to prevent sticking and ensure even baking.

Step 2: Make the Chocolate Cookie Dough

1. In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.
2. In a large mixing bowl, beat the softened butter, granulated sugar, and brown sugar together with an electric mixer on medium speed until light and fluffy, about 2-3 minutes.
3. Add the egg yolk and vanilla extract, mixing until combined.
4. Gradually add the dry ingredients to the wet ingredients, mixing on low speed until a soft dough forms. Be careful not to overmix.

Step 3: Shape the Cookies

1. Scoop about 1 tablespoon of dough and roll it into a ball. Repeat with the remaining dough, placing the balls about 2 inches apart on the prepared baking sheets.
2. Use your thumb or the back of a spoon to gently press an indent into the center of each cookie, creating a “thumbprint.”

Step 4: Bake the Cookies

1. Bake the cookies in the preheated oven for 10-12 minutes, or until the edges are set and the cookies look slightly puffed.
2. Remove the cookies from the oven and immediately use the back of a spoon to press down the centers again if they’ve puffed up during baking.
3. Let the cookies cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.

Step 5: Make the Cherry Ganache Filling

1. In a small saucepan over low heat, combine the dark chocolate chips and heavy cream. Stir constantly until the chocolate is melted and smooth.
2. Remove from heat and stir in the cherry jam or preserves until well combined.

Step 6: Fill the Cookies

1. Spoon or pipe the cherry ganache into the center of each cooled cookie. Fill each thumbprint generously, ensuring the filling reaches the edges.

Step 7: Garnish and Serve

1. Sprinkle the cookies with crushed freeze-dried cherries, powdered sugar, or decorative sprinkles for a festive touch.
2. Allow the ganache to set for about 15-20 minutes before serving.

Enjoy your decadent Chocolate Cherry Thumbprint Cookies with a cup of coffee, tea, or a glass of milk for the ultimate treat!