1. Preheat oven to 450 degrees F.
2. Heat 1 tablespoon of the olive oil over medium heat in a large, heavy skillet. Add the onion and cook, stirring often, until onion is tender (5-7 minutes). Add the fennel and garlic, and cook, stirring often, until the fennel begins to soften (5-7 minutes).
3. Turn the heat to low, cover and cook, stirring often, until the fennel is very tender and sweet (15-20 minutes). Season to taste with pepper. Stir in the fennel fronds, and remove from the heat.
4. Roll out the pizza dough and place on a 12" or 14" pan or large baking sheep. Brush the pizza crust with the remaining tablespoon of olive oil. Spread the fennel mixture over the crust in an even layer. Bake until crust is brown (15-20 minutes).