Rinse, dry, trim and halve green beans. Dice onion, and chop up garlic cloves (unless you're using a jar of minced garlic *see recipe notes).
Whisk heavy cream, salt, pepper, marjoram and gluten free flour together in a small bowl and set aside.
1 & ⅓ cups heavy cream, 1 teaspoon salt, 1 teaspoon ground black pepper, 1 teaspoon marjoram leaves, 2 teaspoons gluten free flour
Measure olive oil into a large skillet or pot and place on medium-high heat. (I normally use a large stock pot. 2 pounds of green beans is a lot and many skillets are too small).
Add green beans, diced onion and slivered almonds to the pot. Sauté 10-15 minutes, until onion softens. Then, stir in minced garlic and sauté 30 seconds longer.
Transfer green bean mixture to a 9x13 inch casserole dish and set aside.
Preheat oven to 350°F.
Place pot (or skillet) back on the stove and reduce heat to low. Add heavy cream mixture and stir constantly until thickened, then remove from heat.
Pour sauce over green beans in the casserole dish. Add half of your parmesan cheese and stir everything together. Bake for 45-50 minutes until green beans are nice and tender!
While casserole bakes, use remaining cheese to make your topping! Place a non-stick frying pan on the stovetop on medium heat. Once hot, sprinkle parmesan cheese into the pan. *Tip: don't overload the pan, cook cheese in small batches.
Once cheese browns, remove pan from heat. After 30-45 seconds, use a spatula to remove fried cheese from the pan and set it aside to cool. Repeat until remaining ½ cup of cheese has been browned.
Crumble cooled cheese into small pieces.
When your casserole is done baking, sprinkle with crispy parmesan (or whatever crunchy topping you've chosen to use). Enjoy!