Start by mixing the flour, baking soda, and salt in a bowl. In another bowl, I cream the butter with both sugars until light and fluffy. Then I mix in the egg and vanilla extract until everything looks smooth and well combined.
I scoop small portions of dough onto a lined baking sheet, spacing them evenly. The cookies bake until the edges are lightly golden but the centers remain soft. Once baked, I let them cool completely so the ice cream won’t melt later.
I place a scoop of vanilla bean ice cream on the flat side of one cookie. Then I gently press another cookie on top, forming a sandwich. I wrap each sandwich tightly and freeze until firm.