Place the grits in a bowl and add 4 cups water; let stand for a minute.
In the meantime, line a 3-quart slow cooker, or larger, with a slow cooker liner. Set aside.
Pour the rinsed grits through a mesh strainer and drain. Then, transfer the grits to the slow cooker.
To the insert of the slow cooker add in 2 cups water, milk, salt, pepper, and half of the cubed butter pieces. Stir to combine.
Cover and cook on LOW for 2.5 to 3 hours, or until the liquid is all absorbed. Stir the grits about 3 to 4 times during the cooking process.
About 20 minutes before the grits are done, set a large skillet over medium heat.
When the skillet is hot, add the bacon pieces and cook until crispy.
Remove bacon from skillet; do not toss the bacon grease.
To the bacon grease add the shrimp, season with salt and pepper, and cook for 2 minutes, or until shrimp turn pink.
Stir in the garlic, lemon juice, onions, and parsley; continue to cook for 2 more minutes.
When the grits are done, remove the cover and stir in the remaining butter and shredded cheese; stir until melted and completely combined.Taste for salt and pepper; adjust accordingly.
Spoon the cooked grits into a serving bowl.
Top with shrimp and bacon.
Garnish with parsley.