Heat a large saucepan over medium-high heat. Add 1-1/2 tablespoons oil to pan. Add onion, and saute 2 minutes, or until tender. Add garlic, and saute 30 seconds, or until fragrant. Stir in flour. Reduce heat to medium, and cook 3 minutes, stirring constantly.
Add wine, scraping the bottom of the pan to incorporate any browned bits. Add stock, stirring with a whisk until smoother, and bring to a boil. Add potatoes. Pierce chile pepper several times with a sharp knife, and add to pan. Reduce heat, and simmer 10 minutes, or until potatoes are tender.
While soup simmers, toss shrimp with 1 tablespoon oil. Season with salt and black pepper. Heat a skillet over medium-high heat. Add shrimp to pan, and cook 2 minutes on each side, or until done. Remove from heat, and set aside.
When potatoes are tender, add corn to pan. Stir in half-and-half. Season chowder to taste with salt and black pepper. Cook over medium heat, until warm. Discard chile pepper. Ladle corn chowder into soup bowls. Top evenly with shrimp. Garnish with parsley.