01 - Remove leaves and stem from cauliflower head. Cut florets into pieces and pulse in food processor until texture resembles rice grains. Set aside.
02 - Heat olive oil and 1 tbsp butter in large skillet over medium heat. Add chopped onion and cook 3-4 minutes until translucent, stirring occasionally.
03 - Stir in minced garlic and sliced mushrooms. Sauté 3-4 minutes until mushrooms soften and release moisture.
04 - Add riced cauliflower to skillet. Stir well to combine with aromatics. Cook for 2 minutes, stirring frequently to coat evenly.
05 - Pour in white wine if using. Simmer 1-2 minutes until almost completely evaporated, scraping up any browned bits from bottom of pan.
06 - Add vegetable broth 0.5 cup at a time, stirring frequently. Wait for liquid to absorb before adding more. Continue until cauliflower is tender but not mushy, about 10-12 minutes total.
07 - Stir in baby spinach leaves. Cook 1-2 minutes just until wilted, stirring gently to incorporate.
08 - Add remaining butter, heavy cream, and grated Parmesan cheese. Stir until fully melted and mixture becomes creamy and well combined. Season with salt, pepper, and nutmeg to taste.
09 - Serve immediately while hot. Garnish with additional Parmesan cheese and drizzle of olive oil if desired.