Make the grits cakes: In a large saucepan, bring the chicken broth and water to a boil over high heat. Whisk in 4 tablespoons of the butter until melted. Gradually whisk in the grits and cook, stirring constantly, until thickened, about 5 minutes. Remove from heat and stir in the Gruyère, Parmesan, and heavy cream. Season with salt. Spread the grits mixture into a 9-inch square baking pan and refrigerate until firm, about 2 hours.

Preheat oven to 375°F. Grease a baking sheet. Whisk the eggs in a shallow bowl. Place the panko in another shallow bowl. Cut the chilled grits into 8 squares. Dip each square in the egg, allowing excess to drip off, then coat in the panko, pressing to adhere. Place the breaded grits squares on the prepared baking sheet. Bake until golden brown, 15 to 20 minutes.

Make the shrimp: In a medium bowl, toss the shrimp with the Old Bay, garlic powder, salt, and cayenne. Heat 1 tablespoon of the olive oil in a large skillet over medium-high heat. Add half the shrimp and cook, turning occasionally, until opaque throughout, 2 to 3 minutes. Transfer to a plate. Repeat with the remaining 1 tablespoon olive oil and shrimp.

Make the cream sauce: Melt the butter in a large skillet over medium heat. Add the tomatoes, bell peppers, onion, scallions, and garlic. Cook, stirring occasionally, until the vegetables are softened, about 5 minutes. Stir in the heavy cream, smoked paprika, Old Bay, and garlic powder. Bring to a simmer and cook until slightly thickened, about 5 minutes. Remove from heat and stir in the Parmesan.

To serve, place a grits cake on each plate and top with the shrimp and cream sauce. Garnish with additional scallions.