When working with the dough, use powdered sugar on your hands and wax paper wrap instead of flour; these cookies are floury enough. The longer you chill the dough, the better it holds its shape. Use unsalted butter, and almost anything other than red currant jelly is too sweet. Mashing the jelly with a fork makes it less likely to bubble up and spill over onto the dough.
Take 3/4 cup softened butter, 1/2 cup sugar, 1 egg yolk, and 1 1/2 cups cake flour. Cream butter and sugar with egg yolk. Fold in flour, knead a little bit, wrap in wax paper, and chill. Roll into 1/2 inch balls, make a small depression in the middle, and fill with jelly. Bake at 325 until golden.