Miam-miam!

miam-miam (pronounced mee-am mee-am) = yummy! yum-yum! mmmmh!
grignoter = to nibble (gree - nee - oh - tay)

Il est toujours en train de grignoter = he's always nibbling

And in the area of French "grignotage", I doubt you can beat PIM's. The delicious cookie, made from a soft biscuit, a jam or mousse filling and a chocolate topping, has a cult following. The classic PIM's collection consists of strawberry and orange flavors, and was recently enriched with pear and chocolate mousse flavors. Although some flavors did not survive (anyone remembers the white chocolate-cherry fiasco?), its manufacturer, LU, keeps the product line alive for the joy of all its fans. It was a great surprise on my recent trip to France, to find out about a couple of interesting additions (which, of course, contributer to filling up my suitcase on the way back):

Coconut Mousse
Lemon Mousse
Tendres Plaisirs ("Tender pleasures")