Place whole peeled potatoes in a Stock Pot and cover with cold water. Bring to a boil, season with 1 Tbsp. salt, and lower to a simmer. Cook until tender and mashable, about 40-60 minutes.

While potatoes are cooking, use a Chef Knife to slice fennel in half lengthwise and remove core. Slice crosswise into ¼”-thick slices. Smash the garlic cloves with the back of the Knife and coarsely chop.

Place Enamel Cast Iron Dutch Oven over medium heat and pour in olive oil. When  hot, add garlic and fennel. Cook, stirring frequently until fennel begins to brown and soften, adding a tablespoon of water if needed to prevent burning. Once fennel is golden and fork tender, add cream, remaining 1 Tbsp. plus 1 tsp. salt, and bay leaf. Bring to a boil, turn off the heat, and cover with lid.

Once potatoes are cooked, remove the Bay leaf from the cream mixture. Drain the potatoes, then use a potato ricer or food mill, add them to the Dutch Oven with the cream mixture. Add butter and sour cream, then stir vigorously to break up the fennel and combine ingredients.

Preheat oven to 500F. Taste and adjust seasoning as necessary. Clean the sides of the Dutch Oven with a rubber spatula, spread the potato mixture evenly across, then use the spatula to make waves. This will create texture when browning. Alternatively, transfer mixture to a separate 8x8 Baking Dish and follow the same instructions.

Bake the mixture until golden brown on top, about 10 minutes. Finish the potatoes with an additional drizzle of hot cream and dusting of fennel pollen or toasted ground fennel seed, if desired.