If desired, line a silicone muffin pan with ham or prosciutto slices. (If using a metal muffin pan, grease muffin cups with olive oil, butter, or nonstick spray.)Whisk together eggs and water with a pinch of salt and pepper until quite smooth. Stir in spinach and any vegetables desired. Pour mixture into muffin cups, filling each cup about ¾ full.Bake at 375 degrees for 15-20 minutes, or until just set in the center. Allow to cool 1-2 minutes in the pan before transferring to a plate.