Preheat the oven to 350 ℉. Line a baking sheet with parchment paper.
Mix together olive oil, garlic powder, onion powder, salt and pepper. Toss the almonds in the mixture.
Spread out on the baking sheet and cook for 8-10 minutes. Stirring after each minute. Be careful not to burn the almonds. When toasted, set aside.
Finely dice one half of a small onion. Place in a microwave safe bowl with 1/2 Tbs vegetable oil. Heat for about 3-4 minutes until onions are soft. Stirring after each minute.
In the bowl with the onions, add 1/4 cup of toasted sliced almonds. Stir in the gluten-free cream of mushroom soup, milk, 1/4 tsp Cajun seasoning, 1/4 tsp salt, 1/4 tsp cracked black pepper.
Pour it into a casserole dish and bake for 25 minutes until bubbly.
Top the casserole with sliced almonds.
Serve.