In a small bowl, combine the yeast with the sugar and 3/4 cup warm water. Let sit for 10 minutes until it begins to foam.
In a large bowl, combine the all-purpose flour, whole-wheat flour and salt and make a well in the center. Add the yeast mixture and the olive oil. Using a fork, incorporate the wet ingredients into the dry ingredients until a dough forms. On a lightly floured surface, continue to work and then knead the dough until it is smooth and elastic, about 8 minutes.
Lightly coat a clean bowl with additional olive oil and add the dough, turning once to coat in oil. Cover and set in a warm place until doubled in size, about 1 hour.
Heat a grill pan over medium-high heat and preheat the oven to 400 degrees F.
Punch down the dough and divide it into 2 pieces. Working with one piece at a time, stretch the dough into a 12-inch circle that will fit on the grill pan. Add the dough to the hot grill pan and cook until stiff and bubbles start to form, 1 to 2 minutes. Flip and cook on the other side until grill marks form and the dough is completely cooked through, 1 to 2 minutes more.
Transfer the crusts to baking sheets and load with desired toppings. Add the loaded pizzas to the oven and cook until the cheese melts (this will vary depending on the type of cheese), about 6 minutes.