Smashed Brussels Sprouts

Bahan-bahan (5 porsi)

• 2 pounds whole Brussels sprouts (ends trimmed)
• 2 tablespoons extra virgin olive oil
• 2 1/2 teaspoons kosher salt (divided)
• ¼ teaspoon ground pepper
• Pinch red pepper flakes (optional)
• 3 tablespoons finely grated Parmesan
• Juice of 1 small lemon (optional)