1 Preheat the oven, put together the baking dish: Preheat the oven to 375℉.
2 Slice the greens: Utilizing a mandoline or a really sharp chef’s knife, reduce the parsnips and carrots diagonally into slices about 1/8-inch thick. Halve the fennel, then reduce into slices about 1/8-inch thick.
three Sauté the aromatics and fennel: Soften the butter in a sauté pan over medium-high warmth. When the butter is foamy, add the shallots, and cook dinner till gentle and translucent, about three minutes. Add the fennel, and cook dinner till simply tender, four minutes. Season with half of teaspoon salt and 1/four teaspoon pepper. Stir within the garlic and thyme, and cook dinner till fragrant, one other 30 seconds.
four Layer the greens: Grease a big (2 quart) gratin dish or a 9-x-13-inch glass baking dish with butter. Layer half of the parsnips within the gratin dish, sprinkle with a pinch of salt and a grind of black pepper.
Prime with half of the carrots, and season with one other pinch of salt and grind of black pepper. Scatter half of the fennel combination on prime of the carrots.
Repeat with the remainder of the parsnips and carrots, ending with the remaining fennel combination. Put aside.
5 Start the béchamel: You will want two sauce pans, one small and one medium.
In a small sauce pan set over medium-low warmth, add the milk and cream.
In a medium saucepan set over medium warmth, add the butter. When the butter foams, whisk the flour into the melted butter, and cook dinner till nutty smelling and lightweight golden in colour, about three minutes.
6 Add the milk to the roux: Slowly whisk the nice and cozy milk and cream slightly bit at a time into the butter and flour combination (roux) till mixed. The sauce must be clean.
Deliver the béchamel to a simmer, maintaining a tally of the warmth and stirring ceaselessly to forestall scorching. It is going to actually begin to thicken because it simmers.
Scale back the warmth to medium-low, and simmer till the sauce is thick and coats the again of a spoon, about four minutes.
7 Take away from warmth and add the cheese: Take away the béchamel from the warmth and whisk within the blue cheese just a few crumbles at a time. Season the sauce with salt, pepper, nutmeg, and a pinch of cayenne, if you’d like slightly warmth. Style and modify the seasoning, if desired.
Eight Add the béchamel to the greens: Pour the nice and cozy béchamel excessive of the greens within the gratin dish and let sit for at the least 15 minutes to permit the sauce to soak into the greens.
Scatter the pecans excessive of the gratin. (The gratin will be made forward up up to now, then refrigerated till able to bake.)
9 Cowl and bake: Snugly cowl the gratin with foil and bake for 45 minutes. Uncover and bake for an additional 20 minutes, or till the gratin is golden brown and bubbly, and the greens are tender when pierced with a knife.
10 Serve: Let relaxation 20 minutes earlier than serving.