Once you've properly washed your fennel with water, cut the bulb in half (as pictured below) and slice into pieces. Cut the entire stalk into pieces as well, and save the fennel sprigs for later. Place it on a baking sheet lined with parchment paper and toss in 1/2 tbsp of olive oil before roasting in the oven for 10-15 minutes at 450°F (230°C).