Preheat the oven to 350°F (175°C).

In a mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until smooth.

Beat in the eggs one at a time, then stir in the vanilla.

In another bowl, combine the flour, baking soda, and salt. Gradually blend this into the creamed mixture.

Fold in chocolate chips if using.

Drop by rounded tablespoons onto ungreased baking sheets.

Bake for 8 to 10 minutes in the preheated oven, until the edges are golden.

Allow cookies to cool on baking sheets for a few minutes before transferring to wire racks to cool completely.

Once the cookies are completely cool, take one cookie and scoop a generous amount of softened ice cream onto the flat side.

Top with another cookie, flat side down, and gently press together.

Repeat with remaining cookies and ice cream.

For best results, freeze the assembled sandwiches for at least 30 minutes before serving.