Stir the grenadine and cranberry juice together in the bottom of a tall collins glass.

Fill the glass almost to the top with ice, packing it in gently so the cubes sit close together.

In a separate cup, stir the half-and-half with the vanilla syrup until smooth.

Hold a spoon upside down with its back just touching the inside of the glass above the ice, then pour the cream mixture slowly over the back of the spoon so it lands on top of the red layer without mixing in.

Repeat the spoon trick with the lemon-lime soda, pouring it even more slowly to float a clear top layer over the cream.

Do not stir the finished drink; held up to the light, it should show three distinct bands of color, red, white, and clear.

Hook the mini candy cane over the rim.

Hand it over with a straw and let her stir it herself at the table, that is half the fun for the kids.