Position two racks in the oven so that they are evenly spaced and preheat the oven to 350°F. Line two cookie sheets with Gefen Parchment Paper.

In a saucepan, combine the chocolate chips, butter, and corn syrup. Place the pan over medium-low heat. Warm the mixture until the butter melts. Don’t let the chocolate get too hot! Remove the pan from the heat and stir the chocolate mixture with a rubber spatula until it is melted and smooth. Using the rubber spatula, scrape the mixture into a large bowl and let cool.

Add the sugar to the cooled chocolate mixture and stir well with a wooden spoon. Stir in the egg and vanilla until blended. Scrape down the bowl with the rubber spatula.

In another bowl, whisk together the flour, baking soda, and salt.

Add the flour mixture to the chocolate mixture and stir with a wooden spoon until blended.

Scoop up a rounded tablespoonful of dough, then use your finger to push the dough onto one of the prepared cookie sheets. Repeat with the rest of the dough, spacing the mounds four inches apart on the cookie sheets. You should be able to fit nine cookies on each cookie sheet. With your fingers, pat the mounds of dough to make them as round as possible so that they will spread into neat circles.

When both cookie sheets are full, bake the cookies until they puff and then begin to sink, 10 to 12 minutes. Don’t overbake them, or they will become too crunchy. Remove the cookie sheets from the oven and set them on wire racks. Let cool for 15 minutes, then use a metal spatula to move the cookies directly to the racks. Let cool completely. Repeat to bake the rest of the dough.

Put the sprinkles and/or other decorations into small bowls. Turn half of the cookies bottom side up and top with a scoop of ice cream. Place a second cookie flat side down on top of the ice cream. One at a time, pick up the ice cream sandwiches and gently press the cookies together to squish the ice cream all the way to the edges. Roll the ice cream edges in the decorations until coated all around.

Wrap each ice cream sandwich in plastic wrap and freeze until firm, at least two hours. Serve with lots of napkins.