Bring broth, milk and salt to a simmer in a medium pot. Slowly whisk in white corn grits. Reduce heat to low and cook, covered and whisking frequently, for 30 minutes. Add shredded cheese (if using) and stir until melted; hold warm until ready to serve.
In a large saucepan, cook bacon over medium-high heat until crisp. Remove from pan with a slotted spoon and drain on paper towels, leaving drippings in pan.
Add shrimp to drippings in pan over medium-high heat. Cook until just pink, about 3 minutes. Remove to a clean bowl.
Deglaze pan with white wine, scraping the bottom of the pan and simmering until wine is reduced by half. Add broth, garlic and half of the scallions and cook until reduced by half, about 5 minutes.
Whisk butter and hot sauce into pan, then return shrimp and bacon and cook until shrimp is heated through, 1–2 minutes.
Serve over grits and garnish with parsley and remaining scallions.