This will be perfect!
Warm up well then ride 2 x 15 minute uphill at power L3. At the top of every minute, shift to a gear that puts cadence under 40. Then, stand and hammer at near maximum effort. Get in the saddle as cadence rises and continue at max effort until cadence is 95 RPM or the effort has lasted 10 seconds – whichever comes first. If cadence hits 95 in under 5 seconds you'll need to shift up a gear. Continue this for 15 minutes for a total of 15 all out efforts. 10 + minutes recovery between. Finish the ride time at an easy pace.
Lynda