Combine lukewarm water and yeast. Let it sit until dissolved (about 5 minutes). You may do so in a standing mixer.
Meanwhile, in a microwave-safe medium bowl, add butter chunks, sugar, and salt, and microwave for about a minute. Stir until everything is melted - the mixture should be warm, not hot. Let it cool slightly if the mixture is hot. Dump everything into the yeast mixture. Whisk the egg into the mixture. Let it cool if it's too hot, let it cool to prevent eggs from curdling. Mix until ingredients are thoroughly combined.
Add about 3 cups of flour and continue mixing by hand or using the dough paddle. Add in enough flour (if needed) to make a soft dough.
Turn the dough onto a lightly floured surface and knead for 6-7 minutes or more if you want airy bread.
Place dough in a greased bowl, turning once to coat the dough in oil. Cover loosely with a clean cloth and let it rise in a warm, draft-free place for 1-2 hours or until doubled. Punch the dough down.
Dump the dough onto a floured board or work surface. Divide it into two pieces, one about half the size of the other. The approximate weight for the larger dough should be about 18-19 ounces and the smaller dough about 9 ounces.
Now divide the larger piece of dough into three equal strands, and then stretch or roll them into an even thickness to an about 16-inch-long rope.
Line up the strands and pinch them together at one end. Braid the strands, crossing the left strand over the middle strand.
Then cross the right strand over the middle strand until the bread is completely braided. Tightly pinch to seal the end.
Carefully transfer the braid to a baking sheet lined with parchment paper. Repeat the same process with the smaller dough.
Brush egg white onto the larger braided dough, then carefully place the smaller braided dough on top of it. Make sure it sits well.
Cover with a kitchen cloth and let rise until puffy, 30-45 minutes, depending on the weather.
Preheat oven to 350℉/177℃.
Whisk together egg yolks and cream, then gently brush the loaf with the egg wash because you don't want to deflate the bread.
Bake in preheated oven for 30-40 minutes or until the loaf is golden brown. If the bread browns quickly, cover it loosely cover with foil.
Let it cool completely before slicing.