In a medium pot, bring the chicken or vegetable broth to a rolling boil. Gradually whisk in the grits to avoid clumping, then reduce the heat to low. Stir continuously until the grits begin to thicken, about 5-7 minutes. Once thickened, stir in the heavy cream and shredded cheddar cheese until smooth and creamy. Keep the grits warm on low heat while you prepare the other ingredients.
In a large skillet, heat the olive oil over medium heat. Once hot, add the diced andouille sausage and cook for approximately 3-4 minutes, or until browned and slightly crispy. Remove the sausage from the skillet and set aside, ensuring to leave the flavorful drippings in the pan.
In the same skillet with the sausage drippings, add the chopped onion, diced red bell pepper, and minced garlic. Sauté over medium heat until the vegetables have softened and released their aroma, about 5 minutes. Stir occasionally to prevent sticking.
To the skillet, add the peeled and deveined shrimp along with the Cajun seasoning, and a sprinkle of salt and black pepper. Cook for 3-5 minutes, or until the shrimp have turned pink and opaque. Once cooked, stir in the sautéed sausage, ensuring everything is evenly coated in the spices.
On each serving plate, spoon a generous helping of the creamy cheese grits. Top with an ample portion of the Cajun shrimp and sausage mixture, allowing the vibrant colors to shine through.
To finish, sprinkle the sliced green onions over the top for a fresh, crisp flavor and a vibrant contrast against the rich dish.