To make the Pizza Dough: In a small bowl, dissolve yeast in warm water. Let stand until bubbles form, about 10 minutes.
In a large bowl, combine flour, oil, salt, sugar, and the yeast mixture. Using lightly floured hands or an electric mixer fitted with a dough hook, mix until a stiff dough has formed. If the dough is too sticky, sprinkle extra flour 1 teaspoon at a time as needed. Place the dough in a large well-oiled bowl and rotate the ball of dough so it is completely covered with the oil. This will prevent the dough from sticking to the bowl as it rises. Cover with a dry kitchen towel and place in a warm part of the kitchen until it has doubled in volume (about 1 to 1 ½ hours). Place dough on a lightly floured work surface, shape into a disc, and knead for five minutes. Use dough immediately or cover tightly in plastic wrap and refrigerate or freeze for a later use. Thaw to room temperature before using.
To make the Garlic White Bean Puree: Blend all ingredients in a food processor until smooth.
To make the pizza topping and assemble the pizza: Preheat oven to 375 degrees F.
In a large skillet, heat 2 tablespoons oil over medium-high heat and sauté onions until soft and lightly caramelized, about 20 to 30 minutes. Season generously with salt and pepper.
In the meantime, toss remaining 2 tablespoons oil with squash and season generously with salt and pepper. Transfer to a large rimmed baking sheet and roast for 30 to 35 minutes until squash is fork tender, turning once or twice with a spatula. Remove from oven and set aside. Turn heat up to 450 degrees F.
Brush a large rimmed baking sheet (approximately 9- x 13- inch) with oil.
Stretch pizza dough into a rectangle and fit it into the prepared baking sheet. Spread a layer of the Garlic White Bean Puree evenly over the rolled-out Pizza Dough. You may not want to use all of the puree, just enough to coat the dough. On top of the dough, arrange the spinach, caramelized onions, roasted butternut squash, and apple slices. Season with salt and pepper, and brush the edges of the crust with olive oil.
Bake for about 15 to 20 minutes, rotating midway, until the crust is slightly browned or golden. Let cool, slice, and devour!