In a stand mixer bowl add half of the whey, sugar, dry yeast and mix it with a whisk. Let is sit in a warm place for 15-20 minutes.
When the yeast mixture slightly rises and you start to see bubbles, add the second half of the warm whey, salt, olive oil, whole wheat flour and about half of the white flour. Using a hook attachment start kneading the dough on the lowest speed of your mixer.
When all the flour has incorporated, start adding the rest of the flour in parts so you have control of the dough’s consistency. At the moment the dough starts to detach from the mixing bowl walls, you can stop kneading the dough. The dough should be soft and slightly sticky.
Coat a clean bowl with vegetable oil and place the dough inside. It’s best to oil the bowl using your hand, that way the dough will not stick to your hand when touching the dough. Cover the bowl with a lid or plastic wrap and set aside in a warm place. Allow the dough to rise for about an hour and a half.
As you can see, our dough has doubled in size and become very airy. Now we need to deflate it and expel the gases. Transfer the dough into a pre-oiled and floured loaf pan. Cover with plastic wrap or a plastic bag and set aside for another 30 minutes (don’t make the plastic too tight, so the dough has room to rise).
After 30 minutes, remove the plastic wrap and place the baking dish into a preheated oven at 375 F degrees and bake the bread for 30-35 minutes. Check the readiness with a skewer inserted into the bread. Let the bread cool in the baking pan for about 5 minutes. Then, very carefully, pull the bread out and let it cool completely.