Chocolate Thumbprint Cookies

Preheat oven to 350 degrees F (175 degrees C). Position racks in the upper and lower thirds of oven. Line 2 baking sheets with parchment paper. (5 minutes)

In a large bowl, cream together the softened butter and powdered sugar using an electric mixer until light and fluffy, about 4 minutes. Beat in the egg and vanilla extract until well combined. (6 minutes)

In a separate medium bowl, whisk together the flour, cocoa powder, salt, and cinnamon until thoroughly combined. (3 minutes)

With the mixer on low speed, gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix. (2 minutes)

Roll the dough into 1 1/4-inch balls. Roll each ball in sanding sugar to coat evenly. Place the sugared balls on the prepared baking sheets, spacing them about 2 inches apart. (10 minutes)

Using your thumb, gently press the center of each ball to create an indentation, about 1/2-inch deep and 1/2-inch wide. (5 minutes)

Bake in the preheated oven, using both the upper and lower thirds, for 8 to 10 minutes, rotating the baking sheets halfway through, until the cookies are set and almost firm to the touch. (10 minutes)

Remove the baking sheets from the oven and let the cookies cool on the sheets for about 15 minutes. (15 minutes)

Once cooled, gently press the center of each cookie again to redefine the indentations, as they may have puffed up during baking. (5 minutes)

For the ganache filling, heat the heavy cream in a small microwavable bowl on HIGH until just steaming, about 45 seconds. (1 minute)

Remove the cream from the microwave and add the finely chopped chocolate. Let the mixture sit, undisturbed, for 2 minutes to allow the chocolate to melt. (2 minutes)

Gently stir the chocolate and cream together until smooth and glossy. Let the ganache cool slightly until it thickens to a pipeable consistency, about 5 minutes. (5 minutes)

Spoon about 1 teaspoon of the cooled ganache filling into the center of each cookie. (10 minutes)

Carefully slide the filled cookies into the refrigerator to set the ganache, about 10 minutes. (10 minutes)

Enjoy your decadent chocolate thumbprint cookies! They will keep for about 5 days in an airtight container at room temperature.