Check under QC Trails menu above. Not aware of 'groomed snow' trails/singletrack to ride in area though, but some are doable.
Most local Fat Biking seems to be off-trail adventure stuff, riding over anything and everything in the Mississippi River bottoms/timberland. Its a blast, technically challenging, not aerobically demanding if that's what you're seeking.
Rumor has a social Fat Bike adventure forming up for this Saturday 28th. Stay Tuned to Lets Ride forum.