Place potatoes in a large pot and fill with cold water, enough to cover the potatoes by 3 inches. Cover and bring to a boil. When it reaches a full rolling boil, uncover it and reduce the heat to medium-high. Boil the potatoes until fork tender, about 25-30 minutes.

Meanwhile, melt the 14 tablespoons of butter in a medium saucepan over medium-low heat.

Add the leeks, garlic, fresh thyme, and fresh rosemary. When the butter is fully melted, reduce the heat to low and allow the aromatics and fresh herbs to infuse the butter for the entire duration the potatoes are cooking, uncovered for about 20 minutes. The butter will simmer very softly, and that’s what you want.

After 20 minutes, pour in the half and half and increase the heat to medium-low. Simmer for another 5 minutes, stirring often.

After 5 minutes, remove the thyme and rosemary stems, leaving as many leaves behind as you can. Add the sea salt and white pepper.

Turn off the heat and puree the mixture using an immersion blender, or regular blender until smooth. Be careful doing this! This stuff is super hot, I don’t want you to splash and burn yourself.

Set the pureed mixture aside, and drain your fork tender potatoes. Return the potatoes back to the pot, and pour in about a cup of the pureed garlic and leek mixture. Mash the potatoes using a masher, adding a little more of the garlic and leek mixture as needed until you reach the consistency you desire. When it’s almost at the perfect consistency and smoothness, throw in the creme fraiche. Stir and mash that around, and if you still need to add some more of the garlic and leek mixture, do so.

When it’s perfect to your liking, season with additional salt and white pepper if needed. Garnish with thyme leaves and remaining 2 tablespoons of butter.

Serve immediately.