Set the broiler to low and position the rack in the middle of the oven.

Bring a large pot of heavily salted water to a rolling boil. Add the artichokes, cover, and boil for 10 minutes. Remove the artichokes from the water and drain them upside down in a colander.

In a small saucepan over low heat, melt the butter. Sprinkle the flour over the melted butter, whisking until combined and the mixture begins to brown, about 45 seconds. Add the milk and cream. Add the Brie one piece at a time, stirring constantly until melted. Add ¼ cup of grated parmesan and season with cayenne, nutmeg, salt, and pepper. When the mix is smooth, remove the pan from the heat.

Place the artichokes standing up in the middle of a small oiled casserole dish. Open the artichokes by gently pulling apart the leaves to make more room for the filling. Fill the artichokes and cover the tops with the sauce. Sprinkle the artichokes with the remaining parmesan, preserved lemon, thyme, and toasted pecans. Place the dish under the broiler and let the artichokes cook for 8 to 10 minutes—rotating the pan as necessary—or until the cheese turns into a golden crust. Serve immediately.