One thing I used to like at Sonic is a cream slush, which is a regular slush with soft serve ice cream. Now those days are over (thank God!), but I can still enjoy a cream slush.
1 oz heavy cream
1 T cream cheese
1 T or so sugar free vanilla syrup (I didn't measure)
1 packet Xylitol (optional, adds texture)
1/2 - 3/4 C sugar free orange soda (or your favorite sugar free soda)
Crushed ice
Just combine ingredients in a blender and pulse the blender until you reach the desired consistency. I prefer mine on the slushy side, but you can also blend continuously it until smooth. I mix mine with our Magic Bullet, which allows me to mix it in the mug and then enjoy. As you drink it down, you can add the rest of the soda from the can.
As an alternative, you can use club soda and your favorite sugar free syrup for different cream slush flavors.