Combine yeast, 1 tbsp flour, 1 tbsp sugar, and 1/4 cup warm water in a medium bowl.

Mix well and let sit for 10-15 minutes until bubbly.

Add 4 cups flour and warm milk to the yeast mixture.

Mix with a wooden spoon until combined.

Cover and let rise for about 30 minutes until doubled in size.

In a mixer, beat eggs, yolks, and sugar until light and pale yellow, about 5 minutes.

Add the yeast mixture to the egg mixture.

Add salt, vanilla extract, lemon zest, orange zest, rum (or brandy), melted butter, and vegetable oil.

Whisk until combined.

Switch to the dough hook and gradually add the remaining 8 cups of flour until the dough pulls away from the bowl.

Transfer dough to a floured surface and knead until smooth and elastic, about 5-10 minutes.

Place the dough in a greased bowl, cover, and let rise in a warm place for 1-2 hours until doubled in size.

Preheat oven to 350°F (175°C).

Butter two 9-inch saucepans and line with buttered parchment paper collars.

Punch down the dough and reserve one-third for decorations.

Divide the remaining dough between the prepared saucepans.

Shape the reserved dough into decorations (crosses, rosettes, etc.).

Let the dough in the pans and the decorations rise for about 30 minutes.

Brush the tops of the loaves with beaten egg whites.

Attach the dough decorations, securing with toothpicks if needed.

Let rise until almost to the top of the pans, about 20-30 minutes.

Whisk remaining egg yolks with water and brush on the surface of the loaves.

Bake for 10 minutes at 350°F (175°C), then lower to 325°F (160°C) and bake for an additional 50 minutes.

Cool in the pans for 30 minutes before transferring to a wire rack to cool completely.