i usually only make yorkshire pudding if i have a roast beef or prime rib cooking, because you will need the drippings. but here is how i would make them( i used to have to make them every day at one of my jobs). this is a smaller version of the recipe i used.
you will need :
3/4 cup flour
3/4 cup milk
3 eggs
1 tsp.salt
about 1/2 cup of the drippings
i do individual ones in cup cake pan
pre heat oven to 450 degrees
mix up all the ingredients except for the drippings
place pan in the oven with a little bit of drippings in each cup cake spot and get the pan and drippings really hot, then take the pan out of the oven and spoon in batter to each hole then place back into the oven for about 10 min or until the puddings are puffed up and start to dry out a little.
you can also make it in a pie pan if you want to make a large one.
there you go , i have a feeling that this recipe will probably be similar to your moms, but this is how i would make them.