In a large saucepan, combine the potatoes and broth.
Bring to a boil, then reduce heat and simmer, covered, for 8 minutes. Gently mash the potatoes in the pot with a potato masher or fork.
Stir in the broccoli and milk, and bring the mixture back to a gentle simmer over medium heat.
Do not let it boil.
In a medium bowl, toss the 2 cups (480 ml) of shredded Gouda and flour together until the cheese is coated. Gradually stir the cheese mixture into the soup until it's completely melted and the soup has thickened.
Season to taste with pepper.
Divide among individual serving bowls and top with fresh winter greens and, if desired, additional shredded cheese.
Shred your own cheese from a block. Pre-shredded cheeses contain anti-caking agents that can make the soup grainy.
Keep the soup at a gentle simmer after adding the milk and cheese.
Boiling can cause the dairy to curdle and the cheese to separate.