Pour Dr Pepper into a resealable container (freezer safe!) and then put it into the freezer so it can freeze and become slushy (overnight or at least 6 hours).
Once the Dr Pepper is frozen break it up and stir it around so it becomes a loose slush. You can let it thaw for a little while if needed.
Create layers of vanilla ice cream and frozen Dr Pepper in popsicle molds.
Place popsicle molds in the freezer and let freeze overnight.
When ready to serve run the popsicle molds under warm water to help release the Dr Pepper Float Popsicles from the molds.