Place the same large skillet used to blanch the asparagus over medium heat and add in the olive oil. Once oil is simmering, add in the onion and red pepper flakes. Lower heat to medium-low and cook the onion, stirring occasionally, until onion is translucent and mainly wilted, about 3 minutes. Add in the garlic cloves and continue stirring until fragrant, about 30 seconds. Season with salt and pepper. Take the skillet off the heat and fold in the cashews, stir, and pour into a large mixing bowl with the butternut squash noodles and asparagus. Toss to combine and top off with pomegranate seeds.