In a medium bowl, sift together flour, sugar, baking powder, and salt.
Add in margarine and make a fine crumbly mixture. Beat in egg and milk; beat just until dry ingredients are moisten. Spoon batter into a generously buttered pan (round, square, loaf).
Spoon pie filling over the batter, then swirl through the batter with a knife.
Bake at 400 F for 25 to 30 minutes, until done.