Add olive oil and butter to large skillet over medium heat. Heat for about 1 minute, swirling pan to coat entire surface. Butter should melt and foam slightly but not brown.
Add cauliflower florets to skillet in single layer if possible. Stir gently to coat in oil and butter. Cook 5-6 minutes, stirring occasionally, until slightly golden on edges and tender but still with slight bite.
Add sliced mushrooms and stir to blend with cauliflower. Cook 4-5 more minutes, stirring occasionally, until mushrooms are tender and most liquid has evaporated. Mushrooms should shrink and turn golden brown in spots.
Stir in minced garlic, smoked paprika, Italian seasoning, salt, and pepper. Cook 2 minutes, stirring constantly to prevent garlic from burning. Garlic should become fragrant but not brown.
Remove from heat. Drizzle lemon juice over vegetables and toss to distribute. If using, sprinkle Parmesan cheese over top while hot. Garnish with fresh chopped parsley.
Notes
Use firm, fresh cauliflower without brown spots. Cut florets uniformly for even cooking.
Fresh garlic essential for best flavor. Pre-minced can taste bitter when sautéed.
For vegan version, use all olive oil or vegan butter. Omit Parmesan or use plant-based alternative.
Add bell peppers, zucchini, or broccoli for variety. Add toasted nuts for extra crunch.