In a medium bowl, toss the shrimp with blackened seasoning, salt, and pepper.
To a large pot over high heat, add oil. Once hot, add the shrimp in a single layer and cook for about 1-2 minutes per side, until seared and fully cooked. Transfer the shrimp to a plate. Set aside.
Reduce the heat to medium. To the same pot, add the bacon. Cook until crispy, 8-10 minutes. Using a slotted spoon, remove the bacon and set it on the plate with the shrimp, leaving the bacon drippings in the pot.
Add the onion, pepper, and celery to the pot with the bacon drippings. Cook, stirring occasionally, until the vegetables are softened, about 3-5 minutes.
Add the garlic and cook for 1 more minute.
Stir in the broth, potatoes, and corn. Increase the heat to bring the mixture to a boil, then reduce the heat to low and let it simmer until the potatoes are tender, about 15-20 minutes.
Pour in the heavy cream and 1 tablespoon of blackened seasoning. Stir to combine.
Carefully transfer about 2 cups of the chowder to a blender and blend until smooth. (Be careful, the liquid will be hot.) Or, use an immersion blender.
Return the blended chowder to the pot. Add the cooked shrimp and bacon to the pot, stirring to warm them through.
Garnish with green onions before serving.