Preheat oven to 375 degrees. Take refrigerated pie crust out and let it warm to room temperature. Open a can of spinach and drain out as much of the liquid as you can from it. Dump the spinach into paper towels and squeeze out more of the liquid. When the spinach is as dry as you can get it place it on a cutting board and chop it finely. In a small skillet melt the margerine and add the chopped onion. When the onion has softened add the chopped spinach and cook until all excess liquid has evaporated. Sprinkle the nutmeg over the mixture and stir until well combined. Set aside and allow to cool. In a bowl combine the eggs milk and pepper. Grate the velveeta and the cheddar cheese. Unroll the crust and put it in a pie pan. Crimp the edges. Pour the spinach mixture into the crust and spread it evenly over the bottom. Top the spinach mixture with the cheese also spread evenly. Pour the egg mixture over the cheese and place the pie pan on a sheet tray. Put in the 375 degree oven for 20 minutes. Then turn the heat down to 325 and bake for an additional 20 minutes or until a knife inserted in the center comes out clean. Let stand for five minutes after removing from the oven. Cut into 6 equal wedges and serve. Leftovers should be refrigerated.
