Happy holidays to you all! As much as I love the holidays, it can sometimes be a little overwhelming to constantly host and cook for crowds at home or cook for various parties and potlucks. This fennel gratin is beautiful enough to serve at a holiday party and easy enough to prepare for your next potluck or get together in the midst of other holiday craziness. Not only is it wonderfully comforting and delicious, it is easy to prepare in advance and very transportable.
The creamy fennel gratin is a wonderful way to use fennel bulbs in cold weather dishes and I imagine that it would be delicious served with fish. I made the delicious fennel gratin for a friend's birthday dinner and it disappeared in minutes! It was really, really good! And it paired surprisingly well with Swedish mulled wine, glögg. If you are planning to transport the dish, you can bake it for 1 hour at home and bake the last 30 minutes just before serving.
Given the large size of the fennel bulbs I was using, I decide to half the fennel bulb and thinly slice it lengthwise, but if you have smaller bulbs, you can cut the bulbs into quarters. A gratin is really one of those dishes that is infinitely easier to prepare if you have a mandoline. Using a mandoline really, really helps here because you want to slice the potatoes into 1/16" inch even slices so that it will cook evenly.
Saute the fennel and leek in butter until soft, seasoned with salt and pepper, fresh thyme, and fennel fronds. Overlap thinly sliced potatoes on the bottom of a buttered 9 x 13 (really a 10 x 13) gratin dish, season with salt and pepper, top with leek and fennel, and add a layer of parmesan.
Repeat once more starting with a layer of potatoes and if you have potatoes remaining, add a final layer on top. Whisk red cayenne pepper, a pinch of nutmeg, and salt and pepper into the milk and pour on top of the vegetables, pressing down with a spatula so that the vegetables are just covered. If you want to emphasize the fennel flavor, you can toast some fennel seeds over medium high heat until fragrant and then grind coarsely using a mortar and pestle and add to the milk before pouring over the gratin.
Fennel gratin with leek and potato
1 lb fennel (about 2 large bulbs), stalks and fronds removed
1.5 lbs yukon gold potatoes or other waxy potatoes, peeled
2 leeks, dark green tops removed or 1 1/2 cups thinly sliced onions
4 tbsp butter
optional 1 tbsp fennel seeds
leaves from 3 sprigs of thyme
2 tbsp chopped fennel fronds
1/2 tsp cayenne pepper
pinch of nutmeg
2 1/2 cups of whole milk
1 1/2 cups of finely grated parmesan
sea salt and freshly ground black pepper
Preheat oven to 425F. Butter a 9 by 13 gratin dish.
Optional Toast fennel seeds in a small saucepan over medium high heat for 3 minutes, until they release their aroma. Using a mortar and pestle, pound the seeds coarsely.
Peel off any browned or bruised outer layers of the fennel bulb. Cut the bulb in half and slice each half thinly lengthwise.
Halve the leeks lengthwise and then chop crosswise into 1/2" pieces, using the white and pale green parts only. Transfer to a large bowl filled with cold water and let sit until dirt falls to the bottom. Rinse thoroughly and drain in a colander.
Heat 1 tbsp butter in a large saute pan. Add half of the fennel slices and saute until soft, about 5-7 minutes. Season with sea salt and pepper. Transfer to a medium bowl. Add 1 tbsp of butter and repeat with remaining fennel slices. Repeat with leeks in two batches. Combine fennel and leeks in the bowl, season with thyme, 1 tbsp fennel fronds, and if using, ground fennel seeds. Taste and adjust salt and pepper as needed.
Slice the potatoes on a mandoline into 1/16" thick slices. Stir cayenne pepper and nutmeg into the milk. Add a pinch of salt.
Arrange potato slices in overlapping rows on the bottom of the gratin dish. Sprinkle with salt and pepper. Add half of the fennel and leek and spread evenly. Sprinkle with parmesan. Top with another layer of overlapping potatoes, season with salt and pepper, top with fennel and leek, parmesan. Top with last layer of potatoes, season with salt and pepper. Pour milk over the top, sprinkle with parmesan.
Cover with foil and bake for 1 hour. As needed, add a little bit of milk to reach the top layer of vegetables, pressing down each time. Remove the foil and lightly press the gratin down with a spatula. Sprinkle with remaining parmesan and continue baking until the vegetables are tender the top is golden brown, 15 to 30 minutes more. Remove from the oven, garnish with fennel fronds. Let stand for 15 minutes before serving.