Step 1

Line a large baking sheet with parchment paper.

Step 2

Using a sharp knife, carefully cut each vanilla wafer in half through the middle, creating two thinner wafers. Place one half of each wafer on the baking sheet.

Step 3

Place about 1/2 cup of chocolate chips in a small microwave-safe bowl and microwave on 50% power for 1 minute. Stir with a fork and return to the microwave for 30-second intervals on 50% power, stirring in between, until the chocolate is silky smooth.

Step 4

When the chocolate is melted, put it in a piping bag with a small round attachment. You can also use a plastic zip-top bag with a corner cut off to create a small hole. Pipe the chocolate onto the upward face of each vanilla wafer half on the baking sheet, placing the second half of each wafer on top as soon as the chocolate is added. Refrigerate for 1 hour.

Step 5

Near the end of the chill time, place the remaining chocolate chips in a medium-sized, microwave-safe bowl. Microwave on 50% power for 1 minute. Add the vegetable oil and stir. Continue to microwave the chocolate in 30-second intervals on 50% power, stirring in between, until the chocolate is silky smooth.

Step 6

Using two forks or dipping tools, dip each wafer sandwich into the melted chocolate, covering it completely. Gently shake side to side as the wafer rests on the fork to sling off any excess chocolate before placing the chocolate-covered cookie back on the baking sheet. Refrigerate for at least 1 hour, until the chocolate shell is completely hardened.