Preheat a grill, grill pan or large nonstick skillet to medium-high. If using a grill pan or skillet, preheat the broiler.
Place the ground chicken in a medium bowl and season with salt and pepper. Add the lemon zest, Parmigiano-Reggiano, finely chopped garlic, spinach, thyme and a drizzle of EVOO, about 2 tablespoons, and combine. Form into 4 patties and cook the burgers until firm and cooked through, about 6 minutes on each side.
If cooking the patties on a grill, place the bread alongside the patties, grill on both sides and remove. If using a grill pan or skillet, broil the bread on both sides until toasted. Rub the toasted bread with the remaining garlic. Place the bread on plates and top with a slice of tomato, then season the tomatoes with salt and pepper.
In the last 2 minutes of the burgers cooking time, divide the sliced artichokes evenly among the burgers, then cover each with 2 slices of provolone. If cooking on the grill, drop the lid to melt the cheese. If cooking on the stovetop, tent your grill pan or skillet with aluminum foil. Place a burger on top of each of the tomato slices and serve immediately.
