Lightly spray an 13x9-inch baking dish with nonstick cooking spray.
In a small bowl, mix together 1 box cherry Jello, ½ an envelope of gelatin (a little over 1 tsp) and 1 cup of boiling water. Stir to completely dissolve gelatins. Stir in in ¼ cup vodka. Pour into the prepared pan and place in the refrigerator to set, about 20 minutes.
While jello is chilling, make white layer mixture. Pour sweetened condensed milk into a medium bowl. Into a smaller bowl, add 2 packets unflavored gelatin and pour ½ cup cold water over it. Let sit for 2 minutes and then pour in 1 cup boiling water. Stir to dissolve gelatin. Pour this mixture into the bowl with the sweetened condensed milk. Stir in peppermint schnapps. Let cool to room temperature (this is to avoid colors running when you pour over red layer).
Pour ⅓ of white mixture (about 1 cup) over chilled red layer. Place in the refrigerator to set, about 20 minutes.
Mix second red layer, repeating process in step 2. Cool mixture to room temperature before pouring over chilled white layer. Place in fridge for 20 minutes. Pour ½ of the remaining white mixture (about 1 cup) over the chilled red layer. Place in fridge for 20 minutes. Mix third red layer, cool to room temperature, and pour over chilled white layer. Place in fridge for 20 minutes. Pour remaining white mixture over chilled red layer (if white mixture starts to thicken while it sits, place in microwave for about 15 seconds). Place in fridge for 20 minutes. Mix final red layer, cool to room temperature, and pour over chilled white layer.
Chill entire dish for an additional 4 hours or overnight before inverting dish onto a cutting board to remove jello (you may have to loosen edges first). Slice into about 36 squares. Top squares with whipped cream and crushed candy canes and/or sprinkles right before serving, if desired.