Step 1Place a cast-iron pizza pan on the middle rack of the oven and heat to 350 degrees.
Step 2Remove the sausage from its casing and saute with 1 tablespoon of olive oil and the fennel seeds in a saute pan over medium heat, breaking apart the sausage as it cooks. Cook until browned, about 8 to 10 minutes. Set aside.
Step 3Trim the radicchio and cut it into three-fourths inch slices. Toss in a bowl with 1 tablespoon olive oil and one-fourth teaspoon kosher salt. Mound the radicchio on the pizza pan in the oven and roast, stirring and turning with a spatula, until it just begins to caramelize, about 10 minutes. Take the pan out, remove the radicchio and set it aside and return the pan to the oven. Turn the oven up to 450 degrees.
Step 4Brush the prepared pizza dough with the remaining olive oil. Spread the sausage then the radicchio evenly over the pizza. . Grind a little black pepper over the top.
Step 5Slide the parchment paper with the pizza onto an inverted cookie sheet or peel, then transfer both parchment and pizza to the hot pizza pan. Cook until golden and crispy, about 12 to 16 minutes, rotating it once halfway through (use the parchment to do so). One minute before the pizza is done, add the burrata slices to the pizza in the oven, so that it gets just melted.
Step 6Remove the pizza from the oven either by pulling out the parchment paper and sliding the pizza back onto the cookie sheet or by taking out the hot pizza pan and placing it on a trivet. Slice and serve hot.