you will note tablespoon should be tablespoonful also did you notice the spelling of margarine.

Melt the margarin, add three tablespoonfuls of flour, and cook until the mixture bubbles. Add one and one-half cupfuls of cold milk gradually, stirring constantly. Stir in the celery and cook twenty minutes in a double-boiler. Add the pimiento chopped and the cheese. Cook the oysters in their own liquor until the edges curl, and add them, cut in small pieces, together with the liquor strained, to the white sauce. Serve in cups made of the following mixture: sift together two cupfuls of bread flour, the salt, and the baking-powder. Mix in the shortening thoroughly and add about three-fourths cupful of milk or enough to make a soft dough. toss on a well-floured board, roll to one-have inch thickness, and cut with a biscuit cutter. Press each biscuit over an inverted greased gem-pan. Bake a delicate brown in a 230ºC . oven. Arrange on a hot platter and fill the cases with the oyster mixture.

I am not sure that a gem-pan is maybe equivalent to our muffin tins.