Mix Jiffy mix with enough water to form a soft dough. Use 2/3 of the dough for the bottom crust; roll out and place in a casserole dish. Bake for 15 minutes at 375 degrees. Meanwhile, drain oysters, reserving liquid. In saucepan, combine washed oysters, butter, salt and pepper. Cook until oysters curl. Add warmed milk and 1/2 of the reserved liquid from the oysters. Spoon oysters and liquid into cooked crust. Roll out remaining dough for top crust and layer over top of casserole. Bake at 375 degrees until crust is golden brown.