The roasted garlic variation will work well. Roasting really mellows the garlic flavour so use more if you are a garlic lover. For a really intense garlic flavour use raw garlic pushed through a garlic press. The flavour will be very different; use only one or two fat cloves. Unless you like gluey potatoes, don't use a food processor or electric mixer. I would leave out the nutmeg and use the buttermilk with the garlic variation. I particularly like the roasted garlic or celeriac variation as a topping for Shepherd's or Cottage Pie.
HERBED: Add sprigs of fresh herbs, bay leaf or celery tops to the water while boiling potatoes, if desired add 1 tablespoon finely chopped parsley, thyme or oregano, or a combination of fresh herbs, while mashing.
07ITALIAN: Substitute herbed olive oil for butter and use hot chicken broth instead of milk.
08PESTO: Omit butter; add 1/4 cup grated Parmesan and 1 to 2 tablespoon basil pesto or sundried tomato pesto.
09ROASTED GARLIC: Brush 6 to 10 unpeeled cloves garlic with olive oil and roast at 3250F for 30 minutes. When cool enough to handle, squeeze garlic out of skins and add to the potatoes while mashing. Add 1/4 cup grated Parmesan, if desired.
10ROOT VEGETABLE: Use only 4 potatoes and add one of the following: 4 medium parsnips, peeled and diced; 2 white turnips, of equal size to the potatoes, peeled and diced; or 1 medium celery root, peeled and diced. Cook with potatoes. Add an extra pinch of nutmeg.