Melt the butter in a large saucepan over medium heat.
2 tablespoons unsalted butter
Add the shrimp, Cajun seasoning, and salt. Cook until the shrimp curls and turns pink, then remove from the pan.
1 pound shrimp, 1 teaspoon Cajun seasoning, 1 teaspoon salt
Pour in the water and milk. Bring to a boil over high heat.
4 cups water, 2 cups whole milk
Stir in the grits. Reduce the heat to low, cover, and cook according to the package directions (usually about 5 minutes). Stir occasionally to prevent sticking.
1 ½ cups instant grits
Remove from heat, and stir in the cheese until smooth and creamy.
2 cups shredded cheddar cheese
Serve warm with the shrimp on top.