Preheat the oven to 400° F and line a large baking sheet with parchment paper or aluminum foil.
Spread the trimmed green beans and sliced mushrooms into an even layer on the baking sheet. Top with the sliced onions.
Evenly spray the vegetables with PAM Non-GMO Avocado Oil Cooking Spray, then season with garlic salt and pepper.
Bake in the preheated oven for 10 minutes, then remove from oven and sprinkle the sliced almonds on top. Return to the oven and bake for an additional 5 minutes or until the almonds are slightly browned and the green beans and tender and beginning to brown on the ends.