Heat the 1 tablespoon of olive oil in a large skillet over medium-high heat.

Add the bulk Italian sausage and the chopped fennel. Cook, breaking the sausage up with a wooden spoon into fine crumbles, until the meat is deeply browned and the fennel is soft and fragrant, about 5 minutes. Remove from the heat.

Generously coat a large, deep ceramic baking dish with vegetable oil spray or butter.

Place exactly half of the brioche bread cubes in an even layer across the bottom of the dish.

Cover the bread uniformly with the caramelized sausage and fennel mixture.

Scatter the chopped, dry artichoke hearts evenly over the meat. Top with the remaining half of the brioche bread cubes.

In a large, heavy glass or ceramic mixing bowl, vigorously whisk together the beaten eggs and whole milk until unified.

Stir in the grated Gruyere, Parmigiano-Reggiano, sliced green onions, Dijon mustard, fresh parsley, and Herbes de Provence. Season aggressively with the kosher salt and coarse black pepper.

Carefully pour this rich custard evenly over the layered bread cubes. Use your hands or a spatula to firmly push the top layer of bread down, ensuring every piece is completely submerged in the liquid.

Cover the baking dish tightly with plastic wrap and chill in the refrigerator for a minimum of 2 hours (or up to overnight). This critical resting phase allows the dense brioche to fully absorb the liquid, preventing a dry, rubbery bake.

When ready to serve, preheat the oven to 350°F. Remove the strata from the refrigerator and discard the plastic wrap.

Cover the baking dish tightly with aluminum foil. Bake for 20 minutes to heat the dense interior and set the edges.

Remove the foil and continue baking uncovered for an additional 20 to 30 minutes. The strata is finished when the custard is fully set in the center, and the top is puffed, shattered, and deeply golden brown.

Allow the strata to rest for exactly 10 minutes before slicing to ensure the molten cheese and custard stabilize.