This Parmesan Pesto Green Bean Casserole is a fun twist on a classic holiday side dish. Serve it up at Thanksgiving, Christmas, Easter, or any other holiday for an unexpected and flavor packed recipe!
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The “typical” green bean casserole that a lot of people find on their holiday tables is traditionally made with cream of mushroom soup and canned fried onions. I grew up on this and there is definitely a nostalgia to it. One year I decided to make it from scratch instead and OH MY! It is just amazing and completely worth the additional steps and time to make it. Sometimes I will skip making my own fried onions and use the canned kind, but I will ALWAYS make the sauce from scratch now.
I am kind of obsessed with basil pesto. I put it on a lot of different things, as evident with all of my basil pesto recipes. It is just so simple and fast to make with a strong and fresh flavor. And I also really like to experiment with combining different flavor ideas together, which is how this Parmesan Pesto Green Bean Casserole was born. The pesto is not too overwhelming but brings just enough flavor to the sauce for something special.
There is always SO MUCH COOKING happening on holidays, but I will always make a green bean casserole from scratch now. What I really love about this recipe is you can easily make the fried onions (or use the canned version) and the casserole itself ahead of time. Just keep the onions separate. Then when you are ready to serve, pop the onions on top and finish baking the casserole. I will spend at least one day making absolutely everything I can in advance for holiday meals so when the day comes, I can spend more time with friends and family, and less time in the kitchen.
To make the Parmesan Pesto Green Bean Casserole, first you bake the fried onion topping (if using). You can also use the canned fried onions, especially if they are more of a tradition for you, or you want to save time. Boil the green beans and then make the creamy pesto sauce. Toss the green beans, pesto, and a little extra Parmesan cheese in the sauce and you are all set!
- Prepare the fried onion topping. Preheat the oven to 475F. Slice the onion thinly. Place onion in a small bowl. Add the remaining fried onion topping ingredients and toss to combine. Use a little milk if necessary for it to just stick together.
- Spread the dredged onion out on a silicone baking mat lined baking sheet. Bake until just golden brown, approximately 20-30 minutes. Toss the onions at least once during baking to toast all sides. When done, set aside.
- While the onions are cooking, prepare the green beans. Bring a large pot of water to a boil over high heat. Trim the beans and cut into 1-2 inch long pieces. Add the green beans to the boiling water and cook until just blanched, 5 minutes. Remove the beans from the hot water. Immediately drain the beans and put them in a large bowl of ice water to stop the cooking process. Set aside.
- Make the pesto if not already done.
- Make the sauce. In a large skillet, melt the butter over medium high heat. Add the mushrooms, salt, and black pepper. Stir to combine and cook until the onions just start to release some liquid, approximately 3-5 minutes.
- Add the garlic cloves. Stir and cook another 1 minute until fragrant.
- Sprinkle the flour on top of the mushrooms and stir to combine. Cook for one minute to slightly toast the flour.
- Add the vegetable stock and cook for one minute. Reduce the heat to medium low and add the milk. Cook until the sauce has slightly thickened, approximately 5 minutes.
- Remove the sauce from the heat and add 1/2 cup of freshly grated Parmesan cheese (reserve the remaining 1/4 cup). Stir to combine until the cheese is melted.
- Add the green beans and basil pesto to the sauce and stir. Season the sauce to taste as needed with additional pesto, Parmesan cheese, salt, or pepper.
- When ready to serve, heat oven to 400F. Place the green bean mixture in a casserole dish. Top with the fried onions and remaining 1/4 cup freshly grated Parmesan cheese. Bake until bubbling, approximately 10-15 minutes. Serve immediately.