For the dough, combine the water, yeast, sugar and olive oil and let stand for 5 minutes until foamy. In a large bowl, mix together the flour and salt. Add the wet ingredients to the dry and stir until it forms a shaggy dough.  Turn the dough onto a lightly floured work surface and knead for 10 minutes until the dough is smooth and elastic. (Alternatively, the dough can be mixed in the bowl of a stand mixer using a dough hook.)

Gather the dough into a ball, transfer to an oiled bowl and cover. Place the bowl in a warm spot to allow the dough to rise until it has doubled in size, about 2 hours.

For the caramelized onions, place 1 teaspoon olive oil and butter in a large skillet over medium heat. Once the butter has melted, stir in the onions and cook until soft and translucent, about 10 minutes. Add the remaining sugar and continue cooking, stirring occasionally, for an additional 30 minutes until the onions are browned and caramelized. If the onions start to burn, lower the heat and add a tablespoon of water.

Heat a gas or charcoal grill on high heat. On a lightly floured work surface, roll out the pizza dough into a rough circle 12-inch diameter circle.

Place the dough directly on the grates and grill for 2-3 minutes with the lid closed until the crust has grill marks and has puffed up. Turn over the crust and grill for an additional 2 -3 minutes.

Remove the crust from the grill and flip it over so the first side that was grilled is facing down. Drizzle with olive oil and arrange the apples, onions, scallions, walnuts and blue cheese on top leaving a 1/2-inch border. Return the pizza to the grill and cook until the cheese has melted, about 2 minutes. Sprinkle with chives before serving.