'Sandwich' work-out

After a slow warm-up, ran 1000 meters at target race pace. then 6 x 300's faster than race pace (1-2 minute recovery between each) then 1000 meters at target race pace. Finish with a slow recovery jog.
My numbers:
1 mile warm-up
1000 @3;19
300's @ 51,53,53,52,52,51
1000 @ 3:19
1 1/2 mile recovery jog
Sandwich multi-layers of speed between slow jogging. mmmmmmmm good!