1Cut bottom off head of garlic. Place cut side down on baking sheet. Place the fennel and potatoes on same sheet. Drizzle with olive oil and sprinkle salt on top. Roast in 375 degree oven for about 20 minutes. Stirring frequently until nicely browned. Remove from oven squeeze the garlic cloves out of the paper and discard paper.
2Bring chicken stock to a boil. Add the fennel, potatoes, and garlic cloves. Cook until fennel and potatoes are soft. Puree with an immersion blender or food processor.
3Stir in thyme, rosemary, lemon juice, lemon zest and pepper. Heat through.
Season to taste.
Garnish with fennel fronds.