In a large bowl, combine 3 cups flour, mashed potato flakes, sugar, salt, ginger or mace, vanilla, and yeast. In medium saucepan, heat milk, water and butter until very warm, 120 to 130 degrees. Add warm mixture, pineapple juice and eggs to flour mixture. Blend at low speed of mixer until moistened. Beat 4 minutes at medium speed. By hand, stir in 3 cups flour to form a stiff dough. On floured surface, knead in 1/2 to 1 cup flour until smooth and elastic, 5 to 8 minutes. Place dough in a greased bowl turning to grease top of dough. Cover loosely with plastic wrap and cloth towel. Let rise in a warm place, 80 to 85 degrees, until light and doubled in size, 1 to 1 1/2 hours. Punch dough down. Divide into 3 parts, form each into a round ball. Place in 3 (8 or 9-inch) round cake pans that have been well greased. Cover and let rise in a warm place until light and doubled insize, about 1 hour. If desired, brush loaves with glaze made of lightly beaten eggs. Also sprinkle with sugar, if desired. Bake at 375 degrees for 25-35 minutes or until loaves sound hollow when lightly tapped. Remove loaves from pan immediately.