In a large bowl, combine oil, mustard, salt, pepper, garlic and rosemary. Add baby potatoes and shallots and toss together.
Spread potatoes and shallots on a parchment-lined baking sheet. Roast in a preheated 425°F (220°C) oven for 45 to 60 minutes, or until lightly browned and tender.
Sprinkle roasted potatoes with parsley before serving.