Combine matzo meal and sugar; cut in margarine or butter with a pastry blender until the mixture resembles coarse meal. Add 1 lightly beaten egg; stir well to combine. Stir in the almonds. Firmly press the mixture on the bottom and up the sides of a 10-inch deep-dish pieplate. (I spray mine with oil, because everything tends to stick for me!) Prick the bottom and sides of the pastry with a fork. Bake at 400 degrees for 7 minutes. Set aside, and let it cook completely.
Cook spinach in a small amount of boiling water for 3 to 4 minutes; drain. Press the spinach between paper towels to remove the excess moisture. Set aside.
Saute onion in oil in a medium skillet until tender. Combine the onion, reserved spinach, and Swiss cheese. Set aside.
Combine the half-and-half and next 5 ingredients in container of an electric blender (I use a handheld blender), and process until smooth. Set aside.
Spread the spinach mixture over the prepared crust; top with feta cheese. Pour the half-and-half mixture over cheese. Bake, uncovered, at 350 degrees for 50 minutes or until set. (Shield with aluminum foil to prevent excessive browning if necessary). Let stand 5 minutes before serving.