Stack bacon slices; slice crosswise into lardons about ¼ inch (5 mm) thick. Peel shallots; slice crosswise into very thin rings. Finely chop parsley; add to oil and set aside.
Fry bacon slices in a medium-size frying pan over medium heat for 8 to 10 minutes, stirring often, or until brown and crisp. Remove crispy bacon to a paper towel, leaving all fat in pan.
Return pan to heat; add shallots. Fry for 5 to 6 minutes or until crisp and golden; drain on paper towels. When cool, mix bacon and shallots; discard bacon fat.
For soup, peel and cut potatoes into cubes; there should be about 3 cups (750 mL). Peel roasted garlic cloves; leave whole.
Heat butter in a large saucepan over medium heat. Add onion; sauté 4 to 5 minutes or until softened. Add broth, potatoes, garlic, salt and cayenne. Cover and simmer over medium-low heat for 20 minutes or until potatoes are tender.
Purée until smooth. Add cream; heat until hot, but not boiling.
Ladle hot soup into warmed bowls. Garnish in centre with a heap of crispy bacon and shallots. Drizzle a little of the parsley oil around the heap.