Line a baking sheet with parchment paper. Arrange the chopped parsnip, carrot and onion separately from each other. (Depending on the size of your baking sheet, you may need a second one to hold all the veggies.)
Place the baking sheet on the middle oven rack, and roast for 30 minutes. (Check after 20 minutes. If the onion is cooking faster, remove it from the sheet and transfer it to a bowl. Stir the remaining vegetables on the baking sheet and return them to the oven.)
Meanwhile, melt the butter (or coconut oil) in a skillet over medium heat. Saute the garlic until fragrant but not browned (1-2 minutes). Add mushrooms and cook, stirring often, until tender and just starting to brown (5-6 minutes). Remove from heat.
When the roasted vegetables are cooked, transfer them and the mushrooms into a food processor. Add the thyme, sage, salt and pepper.
In the food processor, quickly “pulse” the vegetables so they’re blended but still chunky.
Taste and add more thyme, sage, salt and/or pepper, if you like.
Notes
Want to add a touch of sweetness? Try stirring in some raisins, dried cranberries or finely chopped apple after you’ve removed the mixture from the food processor. You can easily double this recipe too... you'll just need a second baking sheet!