If the peas are still frozen, thaw them, but do not cook.

Fill a large bowl with ice water to cool the onions before peeling.

Bring a large sauce pan of water to a boil and add the unpeeled onions. Once the water is back to a boil, time three minutes, drain then add the blanched onions to the ice water to stop cooking. Drain into a colander and move them to a cutting board.

With a small sharp thin-bladed knife, slice off the root end and pinch the other end to have the onion slip out of its skin. Sometimes you also need to cut it away from the skin. Repeat for all of the onions.

Add the peeled onions to a medium skillet, cover with water and boil about five minutes until tender. Drain and set aside.

Heat the cream in a small sauce pan just to hot but do not boil.

In the same skillet that you blanched the onions, melt the butter and over medium low heat, add the flour and stir with a wooden spoon. Cook for about 3-4 minutes or until the raw flour smell is gone and the mixture is light tan in color.

Add the hot cream one third at a time, whisking after each addition. The mixture will be very thick, then less thick then finally on the last addition, smooth and creamy as you whisk.

Bring the heat to medium and add the salt, pepper, cayenne, mustard and nutmeg and whisk to combine.

Add the thawed peas and stir with a wooden spoon. Once the mixture is hot, add the onions and heat just to serving temperature.

Serve immediately.