- Preheat oven to 400°F (200°C). Line a baking sheet with aluminum foil, leaving enough on the ends to create a packet. 
- Peel and discard the papery outer layer of the garlic bulbs, keeping the bulbs intact. 
- Cut off the top ½ inch of each garlic bulb to expose the cloves. 
- Place the garlic heads, cut side up, on the lined baking sheet. Drizzle with oil. 
- Fold the aluminum foil over the garlic, creating a large packet. 
- Bake the garlic for 60-70 minutes, or until the cloves are soft and deep golden brown. 
- Set the roasted garlic aside to cool. 
- Place the potatoes into a large pot. Cover with water. 
- Bring to a boil over medium-high heat. Cook for about 25 minutes, or until fork-tender. 
- Drain the potatoes and return them to the pot, off the heat. 
- Lightly mash the potatoes in the pot. 
- Add the butter and heavy cream to the potatoes. Mash the mixture to your desired consistency. 
- Squeeze all of the roasted garlic cloves into a medium bowl, discarding the remaining skin. 
- Mash the garlic until smooth. (This makes about 1 cup.) 
- Add the mashed garlic, salt, and pepper to the potatoes. Mix well. 
- Serve the mashed potatoes warm, topped with more melted butter and fresh parsley.