Blanch green beans. Take a medium to a large pot, fill with water enough to cover the beans later. Add salt and take it to a boil. Reduce the heat and lower the green beans into the water. Cook on medium heat for 3 minutes.
1 ½ pound fresh green beans, ½ teaspoon salt or more
Remove the beans from water with kitchen tongs or a slotted spoon and lower them into prepared ice-cold water to stop the cooking process. Once cooled to touch, drain in a colander and pat dry the beans with a kitchen towel.
Meanwhile, preheat the oven to 350 F (180C).
Fried onions. While the oven is getting warm, prepare the fried onions. In a large bowl, mix flour, breadcrumbs, salt, and pepper. Toss the onions in the mixture making sure they are fully coated.
1 large red onion, 3 tablespoon gluten-free breadcrumbs, salt and pepper, 3 tablespoon gluten-free flour
Heat oil in a medium or large saucepot (or a wide and deep skillet). When the oil is hot enough (about 375 F) that it is sizzling (make a test by lowering one onion slice into the oil, if sizzling, your oil is ready!)
peanut or canola oil for cooking
Add a bunch of onion slices and fry until they become golden brown turning them over once making sure they are browned on all sides. You may need to do it in batches depending on the size of your pot or skillet. Don't overcrowd the pot.
The process is quick, don’t leave them unattended! Once browned, spread them out on a cooling rack to remove the excess oil making sure the fried onion slices don’t touch one another. The onions will darken even more once cooled.
Make the creamy sauce. In a large skillet, melt the butter over medium heat. Add mushrooms and saute for about 1 minute. Make space in the middle and add garlic, season the mix with salt and pepper. Stir to combine and saute until garlic becomes fragrant and mushrooms golden brown.
4 tablespoon butter, 8 oz fresh cremini, 4 medium garlic cloves, ¼ teaspoon black pepper, ½ teaspoon salt or more
Next, lower the heat and stir in the flour making sure to coat the mushrooms. Pour in ½ of the chicken/vegetable broth, stir and continue slowly adding the broth until all is used.
½ cup vegetable or chicken broth, 2 ½ tablespoon gluten-free flour
Simmer for few minutes and follow with cream, cajun, and parmesan. Stir constantly until sauce has thickened. The sauce will not thicken in the oven later.
½ cup parmesan, 1 teaspoon cajun spice, 1 cup heavy cream
Lower the green beans into the skillet and stir again until well combined. Remove from the heat.
Casserole Assemble and Baking. Place the green beans sauce in a 9 x 13-inch baking dish, add a layer of bacon and cheddar cheese on top. Top with fried onions in the middle or all over the dish (your call!). Cover the dish with foil and bake for 15 minutes. Take off the foil and bake another 5-10 minutes until cheese has melted and the sides bubbly.
7-10 bacon slices, ½ cup cheddar
Serve immediately while warm.