Sweet Potatoes and Greens With Honey-mustard Glaze

1 3/4 to 2 pounds red-skinned sweet potatoes (yams), peeled, cut into 3/4-inch cubes

3 tablespoons Dijon mustard
3 tablespoons honey
1/4 cup (1/2 stick) butter
2/3 cup minced shallots (about 4)
1 pound Swiss chard, stems trimmed, leaves torn into bite-size pieces
Ground nutmeg

Steam potatoes until just tender, about 10 minutes. Cool. (Can be made 3 hours ahead. Let stand at room temperature.)

Blend mustard and honey in small bowl. Melt butter in heavy large skillet over medium-high heat. Add shallots and saut