Preheat a medium saucepan over medium heat, bring the water (and milk, if using) to a gentle boil. Gradually whisk in the grits, reduce heat to low, cover, and simmer, stirring occasionally, until thickened and tender—about 20 minutes. Stir in butter and shredded cheddar, then season with salt and pepper. Keep warm.

While the grits cook, heat a large skillet over medium-high heat. Add the chopped turkey bacon and cook until it starts to crisp, about 3–4 minutes. Stir in the diced chicken ham and beef sausage; continue to cook until the sausage is lightly browned, about 3 minutes more. Remove the meats from the skillet and set aside.

In the same skillet, melt 2 tablespoons of butter over medium heat. Add the minced garlic and the white parts of the green onions; sauté until fragrant, about 30 seconds. Return the cooked meats to the pan, then add the shrimp and sprinkle with Cajun seasoning. Cook, stirring frequently, until the shrimp turn pink and opaque—about 4–5 minutes.

Stir in the lemon juice, chopped parsley, and the green parts of the onions. Taste and adjust seasoning with salt and pepper if needed.

To serve, spoon a generous portion of cheesy grits into each bowl and top with the Cajun shrimp and meat mixture. Garnish with extra parsley and green onions if desired.