Make the Simple Syrup - In a small saucepan, combine the water, granulated sugar and raspberries. You can use fresh or frozen—I chose to use fresh. You do you.
Heat the ingredients over medium-high heat until the sugar has completely dissolved.
Turn off the heat, and let the flavors infuse and cool for 30 minutes. (Set a timer!)
When the simple syrup has cooled off, blend in a blender or food processor, then transfer to an 8 oz. mason jar.
Refrigerate until time to use. (We want it to be cold so that all the ingredients of the mimosa are nice and chilly!)
Make the Mimosa(s) - In a champagne glass (or multiple glasses), measure out 1 ½ oz. raspberry simple syrup and pour in the orange juice.
Top the glass with champagne, and stir with a cocktail spoon, careful so as not to overflow your glass.
Garnish with a few raspberries and a sprig of mint, and enjoy immediately!