Wash the cauliflower and break it up into florets, keeping them as large as possible. Slice the cauliflower into cross-sections (see photos below for reference.)
Preheat the oven to 400º and line a baking sheet with parchment paper.
Arrange the cauliflower steaks on the baking sheet and coat lightly with olive oil or cooking spray. Sprinkle with salt and pepper to taste.
Bake 15 minutes, then flip the steaks and bake for 10 more minutes.
While the cauliflower is baking, you can whip up the pesto!
Add cashews, basil, olive oil, garlic, nutritional yeast, lemon juice, salt, and pepper to a food processor and blend until smooth. This will likely require some scraping the sides to get everything combined.
Full disclosure, you will have a little bit of waste/leftover cauliflower after making your steaks. Just save it for another recipe like these quinoa bowls or cauliflower curry! ;) *Nutritional yeast is absolutely necessary for this pesto – it has a cheesy flavor! You can find it in most major grocery stores, health food stores, and on Amazon.