-Preheat oven to 425 degrees.
-Peel 1 pound of parsnips, then chop into thin slices
-Drizzle parsnips with olive oil and season with sea salt and pepper.
-Arrange on a rimmed baking sheet.
-Roast, shaking occasionally, until caramelized and tender, about 25 minutes.
-Reduce oven heat to 375.
-Cut 2 leeks in half the long way, then wash between the layers.
-Chop into thin half-moon shaped pieces.
-Heat 2 TBS unsalted butter over medium heat in a medium saute pan until melted.
-Add leeks and cook, stirring occasionally until tender, about 5 minutes.
-Remove from heat; add ½ cup white wine and return to heat.
-Let simmer until reduced, about 1 minute.
-Take the leaves off of 5-6 thyme branches until you have 2 TBS.
-Add thyme and remove from heat.
-Stir in roasted parsnips.
-Whisk together the following in a large bowl:
1½ ounces unsalted butter
2 cups heavy cream
5 large eggs
3/4 cup Parmesan
-Season with sea salt and freshly ground black pepper.
-Add leek-parsnip mixture.
-Cut 1 loaf of brioche bread into 1 inch cubes.
-Mix into the large bowl with the other ingredients.
-Butter a shallow 2-quart baking dish, and pour parsnip mixture into dish.
-Cover loosely with parchment, then foil and bake until golden brown and puffed, 50 minutes.
-Remove parchment and foil.
-Sprinkle with another ¼ cup Parmesan and return to oven.
-Bake for 10 minutes more.
-Let stand for 5 minutes before serving.