In a large pot, add the olive oil and bacon and cook until starting to crisp. Drain and set the bacon back in the pot, reserving the bacon fat.
In a large pan, add the butter, bacon fat and onions and saute until soft. Add the cabbage and cook until tender and slightly golden (cabbage will reduce substantially in volume). Add a drizzle of olive oil and season with salt and pepper.
Cook noodles according to the package directions. Once cooked, drain (reserving some of the pasta water).
Transfer the cabbage mixture to the pot with the bacon pieces, then add the noodles to the cabbage pot.
Mix in the sour cream and toss to combine. Add some of the pasta water to moisten pasta, if required.