Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.

1. In a medium bowl, whisk together flour, baking soda, salt, cinnamon, and nutmeg.
2. In a large mixing bowl, cream together softened butter, brown sugar, and granulated sugar until light and fluffy.
3. Beat in the eggs one at a time, followed by the vanilla extract.
4. Gradually mix in the dry ingredients until just combined. Fold in rolled oats.
5. Scoop tablespoon-sized portions of dough onto the prepared baking sheet, spacing about 2 inches apart. Slightly flatten each cookie.
6. Bake for 10–12 minutes, or until the edges are golden and the centers are set. Let cookies cool completely on a wire rack.
7. Match cookies in pairs of similar size. Soften the cinnamon ice cream slightly, then scoop and spread onto one cookie.
8. Top with the second cookie and press gently. Smooth the sides and place on a baking sheet.
9. Freeze sandwiches for at least 2 hours before serving.