🧅 Step 1: Make the Extra-Crunchy Onions
- Soak sliced onions in buttermilk for at least 30 minutes (up to overnight).
- Mix flour, cornstarch, salt, paprika, and garlic powder.
- Heat oil to 350°F (175°C).
- Dredge onions thoroughly, shaking off excess.
- Fry in batches until deep golden and aggressively crispy (about 2–3 min).
- Drain on a rack and lightly salt while hot.
💡 Southern trick: Cornstarch is what keeps these crunchy even after baking.
🥬 Step 2: Prep the Green Beans
- Boil green beans in well-salted water for 4–5 minutes until just tender.
- Shock in ice water, drain well, and pat dry.
🧈 Step 3: Build the Creamy Sauce
- Melt butter over medium heat.
- Add diced onion and mushrooms — cook slow and patient until soft and lightly golden.
- Add garlic, cook 30 seconds.
- Stir in flour; cook 1–2 minutes (no raw flour taste).
- Slowly whisk in milk + cream until thick.
- Remove from heat; stir in sour cream, soy sauce, paprika, salt, pepper, and cayenne.
Taste it.
It should be savory, rich, and slightly tangy.
🥘 Step 4: Assemble
- Preheat oven to 375°F (190°C).
- Toss green beans with sauce.
- Fold in ½ of the fried onions.
- Transfer to buttered baking dish.
- Top with the remaining onions — pile them high.
🔥 Step 5: Bake
- Bake uncovered for 25–30 minutes
- Onions should stay crunchy, sauce bubbling underneath.
🌟 Optional Southern Upgrades
- Add grated sharp white cheddar or gruyère to the sauce
- Toss a handful of crushed butter crackers into the onion topping
- Finish with a light drizzle of hot sauce before serving
Option 1: Make 1 Day Ahead (Best Texture)
- Prepare the green beans and cream sauce as written.
- Combine green beans + sauce and fold in half of the fried onions.
- Transfer to baking dish, cover tightly, and refrigerate up to 24 hours.
- Store remaining fried onions uncovered or loosely covered at room temp.
Day of baking:
- Let casserole sit out 20–30 minutes.
- Bake at 375°F / 190°C for 35–40 minutes (cold dish).
- Add remaining onions during the last 10 minutes.