Preheat oven to 350°F (175°C) and line two baking sheets with parchment paper.
In a bowl, whisk together flour, baking soda, and salt.
In a large bowl, beat softened butter, granulated sugar, brown sugar, and vanilla until light and fluffy.
Add egg and mix until well combined.
Gradually stir in dry ingredients until just combined.
Scoop tablespoon-sized portions onto baking sheets, spaced apart. Bake for 10-12 minutes until golden brown. Cool completely.
Once cooled, sandwich a generous scoop of ice cream between two cookies. Serve immediately or freeze for later.