Preheat oven to 375 degrees.
Slice 3 large onions into strips and caramelize with butter in a skillet set over medium heat for 30-45 minutes, or until tender and sticky. Once finished, deglaze the pan with ¼ up of liquid* while scraping the bottom to losen any cooked on fond. Cook until the liquid evaporates.
Cut bacon into 1" chunks and cook until crisp, set aside.
Boil pasta in salted water, one minute shy of al dente. (~10 minutes, but refer to package instruction)
In large bowl combine mayo, sour cream, garlic powder and pepper in a bowl and stir to combine.
Add bacon, 1 cup of Provolone cheese and caramelized onions and stir further.
Finally mix in noodles.
Pour pasta and sauce into a lasagna pan, sprinkle with remaining 1 cup of cheese and bake uncovered in oven for 20 minutes.
Turn broiler on for final 2-5 minutes and broil till cheese is browning slightly, monitoring closely.
Let pasta rest for 5 minutes and serve.