Combine the flour, yeast, sugar and salt in a large bowl.
Add warmed milk, oil, and egg + yolk to the flour mixture.
Beat on high speed for two minutes.
On low speed, stir in about 1/2 cup more flour until dough holds together.
Knead the dough on a floured surface about 100 turns.
Cover with plastic and let rest 10 minutes.
Line a baking sheet with parchment paper.
Cut the dough into three and roll each piece into a 16-inch long strip. Braid as you would hair, tucking ends under and place on baking sheet. Cover with a towel and rise in a warm spot until double in size – 40 minutes to an hour.
Meantime, prepare egg wash by combining 1 egg yolk with 1 teaspoon water. Preheat oven to 375° F.
Brush loaf gently with egg wash and sprinkle with poppy seeds.
Bake for 25-30 minutes. If top starts to brown too much, cover with a foil tent.