1. Heat the oven to 190C/Gas 5.
2. Cut the Peruvian potatoes in half or in quarters, about the same size as the small new potatoes. Do the same for the red bliss potatoes. Place all potatoes, garlic cloves, shallot quarters and rosemary sprigs on a baking sheet. Season well with salt and pepper and drizzle oil on top. Toss all to combine and coat in oil.
3. Place the potatoes in the oven and roast for about 30 to 40 minutes, shaking the baking sheet occasionally, until the potatoes are nicely browned and fork tender and the garlic cloves and shallots are caramelized.
4. Remove rosemary sprigs and serve immediately.