Preheat oven to 400°F (200°C). Wash and dry potatoes, then rub with olive oil and salt.
Place potatoes directly on oven rack and bake 50–60 minutes until fork-tender. Remove and let cool slightly.
In a skillet over medium heat, melt butter and sauté garlic for 30 seconds until fragrant.
Add shrimp, Cajun seasoning, smoked paprika, black pepper, and red pepper flakes. Cook 2–3 minutes until shrimp turns pink.
Lower heat and stir in heavy cream and cream cheese until smooth and slightly thickened.
Add cheddar and mozzarella cheese, stirring until melted.
Gently fold in crab meat and green onions, then remove from heat.
Slice the top of each potato lengthwise and scoop out most of the flesh, leaving a sturdy shell.
Mash the scooped potato lightly and stir into the seafood mixture.
Spoon filling back into potato shells and top with extra shredded cheese.
Place stuffed potatoes on a baking sheet and bake for 10–15 minutes until bubbly and golden.
Garnish with chopped green onions or parsley and serve hot.