In a large non-stick skillet, heat 1 tablespoon olive oil along with the thinly sliced onions over medium-high heat until they soften.  Season the onions with salt and pepper to taste.  Reduce the heat to low-medium and cook the onions, stirring frequently until the onions are golden and caramelized for about 25 minutes.

Meanwhile, slice the brussels sprouts very thin with a chef's knife, or with a mandolin.

Preheat the oven to 425° F.

Remove the onions from the skillet and set them aside.  Add the shaved Brussels Sprouts with 1 tablespoon of olive oil to the skillet and cook over medium-high heat for 4-5 minutes until the Brussels start to caramelize.   They will finish cooking in the oven, so they should still look green and slightly crisp, not soggy.   Add half the lemon zest and season with salt and pepper and stir to combine.

In a small bowl, mix together the ricotta cheese and remaining lemon zest.

Roughly chop the hazelnuts with a knife on a cutting board.

Roll out the pizza dough on a parchment-lined baking sheet.

Spoon the lemon ricotta mixture onto the pizza dough and spread to cover the dough, leaving a 1/2 inch border.

Layer with the caramelized onions, then the mozzarella cheese, then the Brussels sprouts, the chopped hazelnuts, and top with freshly grated parmesan cheese.

Bake the pizza for 15 to 18 minutes until the dough is crisp and the cheese is melted and slightly browned.

Serve with a white balsamic glaze or honey, if desired.