I've never tried yellow miso before (although I've had miso soup, of course), and had to go to an Asian market to find it. Salty, but not too bad, and a little bit of sweetness.

Anyway.

Ingredients (oh, I used to dream of food what had Ingredients in it when I were a lad . . . ):

2 heads of garlic
1 tbsp olive oil
Kosher salt
1 cup (2 sticks) unsalted butter, room temperature
2 tbsp white or yellow miso
Black pepper
4 pounds Yukon Gold potatoes
1 1/2 C heavy cream

1. Preheat oven to 350F. Cut the tops off the garlic heads to expose the tops of the cloves; place on a piece of heavy-duty foil or parchment paper. Drizzle with olive oil, add salt and pepper, and drizzle a tablespoon of water on and around them so they steam a bit. Wrap the foil or paper over the heads and seal it up. Place on a baking sheet and roast at 350F for 60-75 minutes.
2. When the garlic's cool enough to handle, squeeze the cloves out into a bowl. Add the butter and mash into a paste, then add the miso and mix well. Season with salt and pepper; set aside.
3. Peel and quarter the potatoes; place in a pot and add enough water to cover by 1 inch; season with salt. Bring to a boil, then drop the heat to medium and simmer the potatoes, stirring occasionally, for another 20 minutes until the pieces are very tender (stick a fork in; if it goes in with no trouble, you're done). Drain the potatoes and let them sit for 5 minutes, then put them back in the pot.
4. Heat up the cream in a saucepan until it simmers.
5. Start MASHING THOSE TATERS LIKE THOSE SPUDS OWE YOU MONEY, then add the hot cream and all but about 3 tablespoons of the garlic-miso butter; taste and season with more pepper.
6. Serve topped with the remaining butter.

VERDICT: Quite tasty! Very silky texture and, in fact, a little looser than I usually like mashed potatoes. However, methinks that the leftovers will be a bit tighter.