**Preheat the Oven:**

Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

**Make the Cookie Dough:**

In a mixing bowl, cream together the butter, peanut butter, granulated sugar, and brown sugar until light and fluffy. Beat in the egg and vanilla extract. In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until combined.

**Shape and Bake:**

Roll the dough into 1-inch balls and place them 2 inches apart on the prepared baking sheet. Flatten each ball slightly with a fork in a crisscross pattern. Bake for 8–10 minutes, or until the edges are lightly golden.

**Add the Spider Bodies:**

Remove the cookies from the oven and immediately press a chocolate truffle into the center of each cookie to create the spider body. Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a cooling rack.

**Create the Legs and Eyes:**

Melt the chocolate chips in the microwave in 20-second intervals, stirring between each interval, until smooth. Transfer the melted chocolate to a piping bag or zip-top bag with a small corner snipped off. Pipe 8 legs around each truffle and use the melted chocolate to attach the candy eyes to the truffle.

**Let Set:**

Allow the cookies to cool completely and the chocolate to set before serving.