Broccoli Cheese Soup

Ingredients (11)

• 3 tablespoons unsalted butter
• 2 medium yellow onions, coarsely chopped
• 6 garlic cloves, smashed and peeled
• ½ teaspoon red pepper flakes (reduce or omit if sensitive to spice)
• 1 1/4 teaspoon fine sea salt, divided, to taste
• Freshly ground black pepper, to taste
• 2 pounds broccoli with stalks (3 large or 4 medium)
• 1 large (about 12 ounces) russet potato, peeled and cut into 1 to 2-inch chunks
• 6 cups water
• 4 to 8 ounces grated sharp cheddar cheese, depending on your mood
• Thinly sliced chives or green onions, for garnish (optional)