It's a bit involved, but I think it's worth it. You also end up with a lot of sauce that can be frozen.
I don't think that it tastes like meaty Bolognaise sauce - but it hits the same spot.
Sauce for 800-900g pasta (dry weight). I really suggest a hearty pasta shape, preferably fresh.
2-3 tbsp butter, or oil if vegan
120 g (lightly) toasted walnuts soaked and washed, then chopped quite finely
2 medium carrots, very finely chopped (250g)
1 medium onion,