Peel the shrimp and devein if desired.
Melt 1 tablespoon butter in a large skillet over medium heat. Add shrimp and saute 3 to 5 minutes, or just until they turn pink. Remove the shrimp from the skillet and set aside.
Add the remaining 3 tablespoons butter to the skillet and melt over medium heat. Add the chopped onion and bell pepper; cook 3 to 5 minutes or until crisp-tender. Whisk in the flour and the next three ingredients. Cook the mixture 1 minute, whisking constantly. Gradually whisk in the chicken broth and half-and-half (use coconut milk if you prefer), and continue cooking over medium heat until mixture is thickened and bubbly. Stir in the sauteed shrimp and cook over medium heat, stirring constantly, until shrimp are thoroughly heated. Serve curry immediately over hot cooked rice. Sprinkle with toppings as desired.