Preheat the oven to 350°F. Cook the lasagna noodles according to the package directions, then drain and let cool.
To make the sauce, melt the butter in a large skillet over medium heat. Whisk in the flour, and cook for 3-4 minutes, or until golden brown and bubbling. Add the milk and the chicken broth a little at a time, whisking constantly, and bring the sauce to a simmer. Simmer until thickened. Remove from heat and stir in the salt, pepper, garlic powder, parmesan, and parsley.
To make the filling, mix together the ricotta, parmesan, eggs, salt, pepper, and garlic powder. Stir in the spinach and chicken.
To assemble, spoon about 3/4 cup of sauce into the bottom of a 9 x 13 baking dish. Add three lasagna noodles to cover the bottom, then spread half of the chicken filling over the noodles. Spread six slices of provolone over the top, then spoon 3/4 cup of sauce over the cheese. Repeat the layers again. Top with three more noodles, then the remaining sauce and remaining slices of cheese.
Bake for 40-50 minutes, or until the sauce is bubbling and the cheese is melted and lightly browned. Let cool for 10-15 minutes before serving.