Preheat your oven to 350°F and line two baking sheets with parchment paper for even browning. Cream together softened butter, granulated sugar, and brown sugar until light and fluffy, approximately 2-3 minutes of beating.
Add the egg and vanilla extract to your butter mixture, beating until fully combined and smooth. In a separate bowl, whisk together flour, baking soda, and salt, then fold these dry ingredients into the wet mixture gently.
Fold chocolate chips into the dough carefully to distribute them evenly without overmixing your batter. Drop rounded tablespoons onto prepared baking sheets, spacing them about 2 inches apart for proper expansion during baking.
Bake for exactly 12 minutes until cookies are golden brown at edges but still soft in centers, which is crucial for this cozy ice cream sandwich recipe. Remove from oven and let cool completely on baking sheets for at least 15 minutes before handling.
Once cookies cool completely, spread softened vanilla ice cream on the flat side of one cookie, then press another cookie on top, flat-side down. Mix cocoa powder, powdered sugar, cinnamon, and sea salt together in a small bowl, then dust the edges of your ice cream sandwich generously.
Wrap each sandwich individually in parchment paper and freeze for at least 2 hours before serving, allowing the ice cream to firm up completely. This storage method prevents sticking and maintains that perfect cozy texture throughout serving.