Pre-heat the oven to 450°F.
Slice the cauliflower into two 1-inch-thick steaks and cut into florets so they are about two bites each. Spray with cooking spray and season with salt and pepper. Roast on a baking sheet to golden and caramelized, about 25 minutes.
Puree a few handfuls of kale in a food processor with 1 large clove garlic, olive oil, a fat handful of grated Pecorino cheese, pine nuts and lemon juice, and salt, pepper and nutmeg, to taste.
Arrange the cauliflower steak bites on a platter and top with rounded teaspoonful dollops of pesto.