Prep all the ingredients: remove the squash ends, peel it, cut in half length-wise, scoop out the seeds and then medium dice it; clean and medium dice the potatoes; peel the shallots and carefully cut them into eighths; wash, core and medium dice the apples.
You need 4 teaspoons of minced lemon zest from the lemons. I find one lemon should give you enough zest, but if you need two, just store it covered for another meal. I use a peeler to carefully remove the lemon rind and then a knife to mince into zest.Lately, I've been using my mini food processor to make zest especially if I can use it to chop or mince other ingredients for the same meal. I needed the lemons for making a pan sauce for the protein part of the meal, but if you don't use them, store the lemon(s) in a container with a lid and use for another meal.
Transfer the potatoes, Brussels sprouts and squash to a large bowl. Drizzle with some olive oil, season with salt & pepper, stir to combine and transfer to a sheet pan (baking sheet).You can do this right on the sheet pan but I find it easier to do this in a bowl to keep the ingredients from falling out of the pan. Be sure to arrange the potatoes and squash in a single layer so all the ingredients cook evenly.
Place the sheet pan in the oven and roast for 18 minutes until lightly browned.
Carefully add the apples and shallots to the pan and stir to combine. I like using a spatula for stirring.
Again, you could transfer the roasted potatoes and squash back to the bowl and then add the apples and shallots and stir to combine before transferring back to the sheet pan. This will take a little longer but keeps the ingredients off the floor or off the bottom of the oven and we all know what happens when those oiled pieces of potato end up on the bottom of the oven.
Roast all the vegetables for another 20 minutes or until the potatoes and squash are tender. You can use a knife or a fork to test the doneness.
Add the lemon zest, stir, taste and adjust seasonings with a little salt and pepper.
That's it. You now have a delightful side dish that you can use as the base to a pan-fried piece of chicken, pork chop, or fillet of fish.