Remove your sundae of choice from the freezer and give the sides of the cup a gentle squeeze to loosen the ingredients. Remove the lid and peel off the protective seal. Fish out the packet of toppings and set it aside for later.
Dump the contents of the cup into a blender. Add 1/4 cup of the milk of your choice. Note that you may need to add another 1/4 cup once up and running, but it’s better to start with less liquid (adding too much will turn your sundae into a smoothie). Start your blender and rock it back and forth, somewhere between a shake and a wiggle (or shiggle, as we like to call it), to keep everything moving.
Once things are looking smooth and the texture resembles a soft serve, scoop everything back into your cup, tear open the packet of toppings, sprinkle it on top, and dig in.
For the best (and most delicious) results, prepare the whole cup at once.