Soft, fluffy, with a sweet chewy interior, Portuguese sweet bread is a delightful treat that tantalizes the taste buds with its irresistible taste and texture.
Combine the milk, butter, sugar, and salt in a microwave-safe cup, or in a saucepan. Heat to lukewarm. Set aside.
In a mixing bowl, the bowl of your stand mixer, or the bucket of your bread machine, combine the flour, yeast, and stir to combine.
Add the milk mixture, stirring first to make sure the sugar and salt aren't left in the bottom of the cup or pan. Add the lemon peel, if using.
Add the eggs, plus one yolk, and the vanilla. Mix and knead until the dough is smooth; it'll be very sticky at first. If you're using a stand mixer, beat with the flat beater for about 3 minutes at medium-high speed; then scrape the dough into the center of the bowl, switch to the dough hook, and knead for about 5 minutes at medium speed. It will have formed a ball somewhat, but will probably still be sticking to the bottom of the bowl. If you're using a bread machine, simply let it go through its entire cycle, and skip to step 6.
Lightly grease the mixing bowl, gather the dough into a ball, and place it in the bowl. Cover, and let rise, about 1 1/2 to 2 hours. It will more than double in size. If you're using a bread machine and the dough hasn't doubled in size when the cycle is complete, simply let it rest in the machine for another 30 to 60 minutes.
Lightly grease two 8 x 4" loaf pans.
Gently deflate the dough, and divide it in half. Shape the dough into two loaves and place into the prepared pans. Cover the dough gently with lightly greased plastic wrap or tented foil. (see notes for braided loaves with eggs in the center).
Let the dough rise in the pans for about 2 hours, until it's again nice and puffy. Toward the end of the rising time, preheat the oven to 350°F.
Mix the reserved egg white with 1 tablespoon cold water, and brush some onto the surface of the loaf; this will give it a satiny, brown crust.
Bake the bread for 15 - 20 minutes, until it's a medium golden brown and its internal temperature registers 190°F on a digital thermometer.
Remove the bread from the oven, and gently transfer it to a rack to cool. Cool completely before slicing. Store at room temperature. You may also freeze the loaves for freshness for about 30 days.
Notes
You can substitute active dry yeast for instant yeast in this recipe. However, you'll need to activate it in warm water before adding it to the dough. Use 1 packet (2 1/4 teaspoons) of active dry yeast and dissolve it in 1/4 cup of warm water with a pinch of sugar. Let it sit for about 5-10 minutes until foamy, then proceed with the recipe as instructed.
The dough will be very sticky at first but will tighten up as the flour has more time to absorb the water. The wet dough also makes it easier for the yeast to rise and double in size over a drier dough so resist the urge to add more flour if the dough seems too sticky heading into the first rise. Also, if you prefer not to use milk, it may easily be substituted for water.
For 2 smaller braided loaves, start at step 7 in the instructions. Divide the dough into two, divided each half into thirds and roll it out into rope strands, and then braid it by weaving the strands. Then form the braided strands into a circle and place a plain (or dyed) hard-boiled egg into the center, and then continue with step 8 of the instructions. The bake time should be roughly the same.
For one large braided dough, divide into thirds and roll it out into long rope strands, and then braid it by weaving the strands. Tuck the ends under the loaf to secure. Place two to three plain (or dyed) hard-boiled eggs into the loaf at intervals, and then continue with step 8 of the instructions. The bake time should be roughly the same.