Preheat your oven to 350°F. Line a baking sheet with parchment paper.

In a medium bowl, whisk together the flour, baking soda, and salt.

In a large bowl, cream together the softened butter, granulated sugar, brown sugar, and vanilla extract until light and fluffy.

Add the egg to the butter mixture and mix until well combined.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Fold in the red and blue sprinkles gently.

Using a tablespoon, scoop out dough and place on the prepared baking sheet, spacing them about 2 inches apart.

Bake for 10-12 minutes, or until the edges are golden and the centers are set. Remove from the oven and let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.

Once cookies are cool, take one cookie, add a scoop of vanilla ice cream, and top with another cookie to create a sandwich. Repeat with remaining cookies and ice cream.

Place the sandwiches in the freezer for at least 30 minutes to firm up before serving.