Season shrimp with salt and pepper, to taste; set aside.
Heat olive oil in a large oven-proof skillet over medium high heat. Add garlic, onion and oregano, and cook, stirring often, until onions have become translucent, about 3-4 minutes. Stir in orzo until lightly browned, about 1-2 minutes.
Stir in chicken broth and 1/2 cup water. Bring to a boil; cover, reduce heat and simmer until pasta is cooked through, about 10-12 minutes. Stir in tomatoes, peas, lemon juice and shrimp. Sprinkle with Parmesan.
Place into oven and bake until shrimp are cooked through, about 12-14 minutes.