Place a medium Dutch oven over medium heat. Add the olive oil, shallots, garlic and 1/2 teaspoon salt and cook, stirring occasionally with a wooden spoon, until the shallots are soft and fragrant, about 4 minutes. Add the rice and saffron and stir to combine and to coat the rice in the flavorful oil. Toast the rice for 2 minutes, stirring often. Add the white wine to the pan and cook, stirring constantly, until almost all the liquid is absorbed. When the wine is absorbed, reduce the heat to medium-low and begin adding the broth 3/4 cup at a time, stirring often between additions (to release the starches) and waiting until the broth is almost entirely absorbed before incorporating the next addition. This will take about 20 minutes total.
When the last addition is almost absorbed but there's still a thick liquid surrounding the rice, stir in the Parmesan, cranberries, butter, radicchio, 1/4 teaspoon salt and 1/8 teaspoon pepper. Stir until the cheese and butter are melted and the radicchio is wilted. The mixture should still have movement and not be too stiff; add a bit more broth as needed to achieve the desired consistency. Serve with additional grated Parmesan if desired.