Are you sure it's not, "1 cup cake meal," or something like that? We have looked everywhere - in dozens of kosher books, in Passover books, in Passover dessert books, online, offline, and in our sock drawer - and have not come up with any reference to cupcake meal.
Cake meal, for those not clued in, is matzoh bread that has been commercially ground to a fine powder. Matzoh is the flat, unleavened bread that is eaten during Passover, and it can be ground fairly coarsely (in which case it is generally called matzoh meal) or finely (and called cake meal or matzoh cake meal). Matzon meal and cake meal are used to bake pancakes, fritters, dumplings, puddings, pastries, and cakes during the Passover season, when foods made with leavened or even possibly fermented grains are forbidden.
Marcy Goldman, author of A Treasury of Jewish Holiday Baking, says cake meal is often blended with potato starch in cakes to produce the best balance between body and tenderness in the finished cake. Although cake flour can be ground very finely, Goldman recommends a medium grind, as it tends to produce a moister cake.
Now, getting back to your cup cake meal, the only possibility we can think of is that some manufacturer somewhere produces a cake meal that is so delightfully special, so magnificently ground, or so completely like all the other cake meals on the market, that they gave it the special name of cupcake meal to stand out on the shelf. If you can find it, great. Otherwise, use any cake meal you like.