Steam riced cauliflower until tender, about 8 minutes. Drain well, pressing out excess moisture.
Stir cream and cheddar into the cauliflower until smooth. Season with salt and pepper. Keep warm.
In a skillet over medium heat, cook bacon until crisp. Remove bacon, leaving fat in the pan.
Season shrimp with Cajun seasoning. Add 1 tbsp butter to the skillet and sear shrimp 1–2 minutes per side until just pink. Remove and set aside.
Add remaining butter and garlic to the skillet, cooking 30 seconds until fragrant.
Pour in broth and lemon juice, simmering 2–3 minutes until slightly reduced.
Return shrimp and bacon to the skillet, tossing to coat in the sauce.
Spoon grits into bowls, top with shrimp and sauce, and finish with green onions.