First, soak the cashews. You can soak them in cool water for 8 hours or overnight. Or in boiling water for about 30 minutes.
When the cashews are ready, start the onions. Heat the olive oil on medium high in a large non-stick skillet.
Add the sliced onions to the skillet, toss them and saute them for about 5 minutes until they start to soften. Reduce heat to medium. Then press the onions with a spatula or spoon into the bottom of the skillet. Leave them alone for 2-3 minutes until they start to brown.
Pour the agave syrup on to the onions, then add the shallots and garlic. Toss everything together, then press back into the bottom and leave alone for a few more minutes. Repeat tossing and pressing the onions until they are completely caramelized. It will take about 15-20 minutes.
While the onions are caramelizing, make the sauce. Drain the cashews and add them to a blender. Then add the vegetable broth, liquid aminos and celery salt to the blender as well. Blend on high, scraping down the sides as needed until the sauce is completely smooth and creamy. Set aside.
Now cook the pasta according to package directions. Drain when it's done and return it to the pot.
Once the onions, pasta and sauce are done, pour the onions and sauce onto the pasta. Toss to combine. Add the chives and a few pinches of salt and pepper. Stir together, then taste and adjust seasoning. Serve with extra chives on top if you want!