Soften yeast in water. Combine flour, sugar, nutmeg, salt and lemon rind in a large bowl. Make a well in center. Add yeast mixture, milk, eggs, egg yolks and combine completely. Beat in butter until dough forms a ball. Place on floured board; incorporate more flour if necessary. Knead until smooth and elastic. Stir dough in well buttered bowl and turn so all surfaces are buttered. Cover with a towel and let rise 1 1/2 hours or until doubled in bulk. Brush baking sheet in butter. Punch down on lightly floured board. Knead, then pat into a 14" cylinder. Place on baking sheet and form into a large ring. Press trinket into dough so that it is hidden. Set aside, covered with a towel, to rise 1 to 1 1/2 hours. Before baking, brush top with the egg milk mixture. Bake in a preheated 375 degree oven for 25 to 30 minutes, or until golden brown. Cool on wire rack. Beat icing ingredients until smooth. Spread over top of cake, letting drip down sides. Immediately sprinkle sugars over icing in 2" wide strips of purple, green and yellow stripes.

*Colored sugar is sold in baking supply houses. If you can't find it, tint icing with food coloring.