Place the medium saucepan on the stove and bring the chicken broth to a boil. Stir in the stone-ground grits and reduce the heat to low. Cook the grits for about 20-25 minutes or until they are thick and creamy, stirring occasionally.
Heat the olive oil over medium heat, in a large skillet. Put the chopped onions into the pan and sauté them until they turn translucent, which usually takes around 2 to 3 minutes. Then cook for an additional 30 seconds until fragrant by adding the minced garlic.
Use Cajun seasoning, salt, and pepper to season the shrimp. Place the seasoned shrimp into the skillet and cook for approximately 2-3 minutes on each side, or until they become pink and opaque. Take the shrimp out of the skillet and set them aside.
Melt the butter over medium heat, in the same skillet. Pour the heavy cream into the skillet and bring it to a gentle simmer.
Gradually whisk in the cheddar and Parmesan cheese until they are fully melted and the sauce becomes smooth and creamy.
Return the cooked shrimp to the skillet and toss them in the cheese sauce.
To serve, divide the creamy grits among plates and top them with the shrimp and cheese sauce mixture. Garnish with chopped parsley for added freshness.