Pat the chicken pieces very dry with paper towels — dry chicken sears; wet chicken steams. Toss with 2 tablespoons of the blackening seasoning until every piece is well coated.

Heat 2 tablespoons of the olive oil in a large skillet over medium-high heat until shimmering and nearly smoking. Add half the chicken in a single layer and sear 3–4 minutes per side without moving it, until deeply browned with a dark crust. Transfer to a plate. Repeat with the remaining chicken, adding the last tablespoon of oil if needed. Work in two batches — crowding steams the chicken instead of blackening it.

In the same skillet (don't wipe it out — the fond is flavor), add the corn, onion, and bell pepper. Cook, stirring occasionally, 5–6 minutes, until the corn is charred in spots and the vegetables are softened. Add the garlic and the remaining 1/2 tablespoon blackening seasoning; cook 1 minute more until fragrant.

Pour in the chicken broth, scraping up every browned bit from the bottom of the pan with a wooden spoon. Let it simmer 1–2 minutes until slightly reduced. Those browned bits are the backbone of the sauce.

Reduce the heat to low. Stir in the heavy cream and simmer gently 1 minute. Take the skillet OFF the heat and sprinkle in the Parmesan a handful at a time, stirring until melted and silky. Adding cheese off the heat keeps the sauce smooth instead of grainy.

Return the chicken and any juices from the plate to the skillet. Stir in the green onions and simmer gently 1–2 minutes until the chicken is heated through and the sauce coats everything. Serve over rice with extra green onions.