Classic Cauliflower au Gratin

Ingredients (8)

• + 1 large head cauliflower, cut into bite-size pieces add to pantry
• + 1 cup light sour cream add to pantry
• + 1 cup shredded Cheddar cheese add to pantry
• + ½ cup diced onion add to pantry
• + 3 tablespoons melted butter add to pantry
• ✓ 2 tablespoons red pepper flakes, or to taste
• + ¼ teaspoon salt add to pantry
• + ½ cup panko bread crumbs add to pantry