In a blender, pour in the fresh squeezed lemon juice and add in the ice.
To the ice, pour in the prosecco and gin. Close the lid, then blend until very smooth and there are no remaining large ice chunks. Pour into a glass (coupe, highball, or wine glass) garnished with fresh lemon wedge.
Notes
Use fresh lemon juice, not from the bottle or concentrate. A traditional French 75 drink always uses french lemon juice. To be frank, fresh tastes better!