How to Make It
Soak the skewers in water for 15 minutes. Heat oven to 400° F and line a rimmed baking sheet with foil or parchment.
Peel and quarter the potatoes and place them in a large pot. Add enough cold water to cover and bring to a boil. Add 1 teaspoon salt, reduce heat, and simmer until tender, 15 to 18 minutes. Add the peas and simmer until heated through, about 1 minute. Drain the potatoes and peas and return them to the pot. Add the milk, butter, ¾ teaspoon salt, and ¼ teaspoon pepper and gently mash.
While the potatoes are cooking, cut the sausage on the diagonal into 1-inch chunks. Core and cut the apples into chunks.
Alternately thread the sausage and apple chunks onto the skewers and place on the baking sheet.
Brush the skewers with 2 tablespoons of the maple syrup and roast for 10 minutes. Brush with the remaining 2 tablespoons of maple syrup and continue to roast until the apples are tender but still hold their shape, 10 to 15 minutes more. Serve with the smashed potatoes and peas.