Peas and cream is a very settling plain food that is great to eat when you're not feeling well. Or better yet, to earn you points when you make it for someone else who is feeling under the weather.
After making this a few times you'll get a feel for exactly how long you should wait between steps, but try about 1 minute between ingredients as a starting point.
The sauce is just a simple white sauce. The first step in preparing it is to melt some butter in a pot. When that's done, add an approximately equal amount of flour and stir well to remove all of the lumps. Let this cook for a moment over low heat. Slowly pour in some warm milk (a cup or so) while stirring. Hopefully you've now got a nice creamy sauce with no lumps or crunchy bits. To complete the tastiness, stir in a can of peas (juice and all).
To serve, put this on top of some plain toast and present with some form of soothing drink (I recommend water).
There, you've hopefully provided some ill person (or yourself) with some calories they can actually keep down.
I'm not sure of the origins of this wonderful comestible, but I'd guess that it is French.
wertperch informs me that this is probably an English dish.