Sandy’s tips and substitutions:

• Storage: Store leftover mashed root vegetables in an airtight container in the fridge for 3-4 days or in the freezer for up to 2-3 months. Thaw and reheat, covered with foil, in a 350°F oven for 20-30 minutes, or until heated through.
• Make ahead: The potatoes, parsnip, rutabaga, and onion can be boiled, cooled, and stored in an airtight container in the fridge the day before, ready to be reheated and mashed with the remaining ingredients for quick and easy serving.  
• Reuse leftovers: Use any leftovers to make delicious potato pancakes or fritters for breakfast alongside scrambled egg and crispy bacon! It would also make a fabulous topping for Shepherd’s pie. 
• Don't Overcook: You should be able to easily pierce a piece vegetable with a fork, but it shouldn't be falling apart. Overcooked vegetables become waterlogged and can make the mash gluey.
• Cut the veggies accordingly: Ensure the rutabaga and parsnips are cut into relatively uniform pieces. This ensures they all cook at the same rate, so you don't end up with some pieces mushy and others undercooked. The red potatoes can be a little larger. Hand held mixer: This small kitchen appliance also works great for mashing the potatoes. Just don't over-mix and you will have chunks!
• Mashing tool: A standard potato masher is perfect for the "smashed" texture and gives you more control over the texture you desire. I don’t recommend using a food processor as this will overwork the starches and turn your mash into a sticky, glue-like paste. 
• Use the salted cooking liquid IF NEEDED: Reserve a cup of the starchy cooking water. When mashing, you can use a splash of this hot liquid to adjust the consistency instead of milk or cream. It adds flavor and helps create a lighter texture.

Variations:

• Pop of freshness: Stir in freshly chopped herbs at the very end. Chives, parsley, or dill work wonderfully and add a bright, fresh contrast to these earthy vegetables.
• A touch of sweetness: A tablespoon of maple syrup or honey can beautifully enhance the natural sweetness of the parsnips and rutabaga.
• Add crunch: For a textural contrast, top the finished dish with crispy fried shallots, toasted breadcrumbs, or chopped walnuts or pecans.
• For a chunkier texture: Use a standard potato masher and only press a few times, leaving plenty of vegetable pieces intact.
• For a smoother mash: pass the cooked vegetables through a ricer or food mill before adding the butter and cream cheese.
• Infused butter: An easy way to add extra flavor to this dish is to use compound butter instead of regular butter. Alternatively, you could melt the butter separately to the rest of the ingredients with a few sprigs of fresh thyme, rosemary, or a couple of smashed garlic cloves. Let it sit for 10 minutes off the heat before straining out the solids. This creates a beautifully flavored butter that will perfume the entire mashed root vegetables.