Prepare. Preheat your oven to 400f. You can prep your baking sheet with nonstick spray or the method of your choice. If you have not done so, cube your potatoes and slice your squash.
Toss. Place your potatoes into a large bowl. Add half of the olive oil, salt, and pepper to the bowl and toss the potatoes. Then repeat this process with the remaining olive oil, salt, and pepper. Transfer the tossed ingredients to your prepared baking sheet, evenly spreading them out, and bake for 10 minutes .
Salmon. Carefully remove the baking sheet from your oven and use a spatula or similar item to push the baked potatoes to the side, making room for the other ingredients. Place the salmon fillets in the vacated area of the pan, leaving room between the fillets. Then evenly place the sliced squash in remaining open areas.
Topping. In a small bowl, use a whisk to combine together your melted butter and pesto to make your pesto butter. Drizzle the pesto butter over each of the salmon fillets.
Bake. Return the baking sheet to your oven and continue to bake until the salmon has baked through.
Serve. Let the salmon rest for a few minutes after taking it out of the oven. The remove the salmon from the sheet pan and serve with the other ingredients.