Preheat the oven to 425 degrees F. Spray a 9-inch spring form pan with nonstick spray. I also like to wrap the bottom edges in foil, just so nothing leaks out!
Cook the bucatini according to the pasta directions, shaving 1 to 2 minutes off the cook time so the pasta is al dente. Drain the pasta and let it cool slightly. You can give it a quick spritz of olive oil so it doesn’t stick together, if necessary.
In a large bowl, whisk together the milk with the parmigiana, eggs, garlic, pepper, salt, 1 cup of the provolone and half of the mozzarella. Stir until combined. Add the cooked pasta to the bowl and toss well, until all the pieces of pasta are covered with the mixture. Transfer the pasta and cheese mixture to the spring form pan. Sprinkle the remaining provolone and mozzarella on top.
Bake the pie for 35 to 45 minutes, or until the cheese is golden and bubbly and the center is set. Remove the pie and let it cool for 10 to 15 minutes. Gently release the spring form pan (use a sharp knife to cut down through any pieces stuck to the sides). Slice the pie into 6 or 8 wedges and serve immediately with more cheese for sprinkling.