Puree Mangoes. Remove the skin from mangoes and cut into cubes. Discard the pit. Put the mango pieces in a blender and puree. (You can skip this step and purchase mango puree from your local health or specialty store.)
Freeze Mango Puree. Pour mango puree into an ice cube tray. Put in freezer uncovered for several hours until completely frozen.
Making Mimosas. Pop the frozen mango ice cubes out of the tray and into a bowl.
Pop Out Mango Cubes. The mango ice ices thaw quickly, so use what you need and transfer the remaining frozen mango cubes into a sealed freezer-safe container and return to the freezer.
Top with Champagne. Put one mango cube into a champagne flute. Pour sparkling wine over it. Let it rest for a moment to give the mango ice cube the chance to melt into the bubbly.