3 tablespoons dijon mustard
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 sauté until fragrant, about 1 minute. Add chard; toss until barely wilted, about 2 minutes. Add potatoes and mustard mixture; toss until heated, about 2 minutes. Season with nutmeg, salt and pepper.