Let's Get Started
Toss the sliced fennel with olive oil, then place it on a baking sheet and roast it at 450 degrees for roughly 20 minutes, or until it gets tender, golden, "buttery and melty" (as Aaron astutely puts it).
Now let's get to that beautiful caramelization! Heat a large skillet over medium-high heat. Put a splash of olive oil in the pan, then throw in the sliced onions, stirring occasionally, until the onions are lightly golden. Reduce the heat a bit, season aggressively, and continue to cook the onions until they are lightly caramelized (this should take about 25 minutes).
Get Your Toppings On
We suggest you cook your pie at the highest temperature your oven can reach. If you're using a pizza stone, you'll want it to be in the oven during the pre-heat. Cook the pizza until the crust is crisp and bubbly.