Combine 1/2 cup all-purpose flour, whole wheat flour, undissolved yeast and salt in a large bowl. Heat milk, water, honey, and butter until very warm (120° to 130°F). Gradually add to flour mixture. Beat 2 minutes at medium speed of electric mixer, scraping bowl occasionally. Add egg and 1/2 cup all-purpose flour; beat 2 minutes at high speed. Stir in enough remaining flour to make a soft dough.
Knead on lightly oiled surface until smooth and elastic, about 8 to 10 minutes. Cover; let rest 10 minutes.
Shape dough into smooth ball; flatten to 9-inch round. Place on greased baking sheet. Cover; let rise in warm, draft-free place until almost doubled in size, about 1 hour.
Writing Mixture: Combine softened butter, flour and water in a small bowl. Stir to make a smooth paste. Transfer Writing Mixture to a resealable bag. Cut the tip.
Brush dough surface with beaten egg and water. Write your message on bread with Writing Mixture squeezed through resealable bag. Bake in a preheated 375°F oven for 30 to 35 minutes or until done. Remove from sheet; cool on wire rack.