How to Make It
Melt 2 tablespoons of the butter in a large pot or Dutch oven over medium heat. Add the fennel and onion. Cook, stirring frequently, until soft, 8 to 12 minutes.
Add the rice and stir until combined. Add the wine, ¾ teaspoon salt, and ¼ teaspoon pepper. Cook, stirring, until the wine is evaporated, 1 to 2 minutes. Add 1 cup of the broth at a time and simmer, stirring occasionally (and waiting until each addition is absorbed before adding the next), until the rice is tender, 20 to 25 minutes.
Add the shrimp and cook, stirring, until opaque throughout, 2 to 4 minutes. Remove from heat and stir in the Parmesan and the remaining 2 tablespoons of butter.
Serve warm topped with the fennel fronds.