Cute, cozy mittens.
One version is stockinette stitch with hearts around the cuff worked in stranded colorwork.
Second version is single color garter stitch.

Description from book:
Warm cosy mittens! This pattern makes both the heart mittens and the garter stitch mittens.
Just remember when working in rounds, to get garter stitch it is knit one round then purl the next round and repeat these two rounds. While to get the stocking stitch for the heart mittens, knit every round.
For those wanting to use up oddments, the hearts use under 20g.