Place the potatoes in a heavy bottomed pot and cover them with cold water. Add the garlic, rosemary, chili flakes, lemon and salt. Bring the pot to a boil over medium high heat and reduce the heat to a simmer. Cook the potatoes until they are fork tender about 18-20 minutes.
Drain the potatoes and discard the garlic and the rosemary sprigs. Spread the potatoes out onto a baking sheet to cool slightly. When the potatoes are cool enough to handle, gently smash the potatoes with the bottom of a glass cup (anything flat will work).
Drizzle the potatoes with the olive oil and place them in the oven for 15-18 minutes. Remove the potatoes and sprinkle the tops of them with the parmesan cheese (really good parmesan from the cheese counter is preferred as shelf stable pre grated parmesan cheese simply won’t melt correctly). Return the potatoes to the oven and bake them for another 5-6 minutes or until the cheese is bubbly and golden.
Remove the potatoes from the oven and allow them to cool slightly for about 2-3 minutes. Sprinkle them with the black pepper and the chives then transfer them to a serving platter.