In a medium bowl, stir together the shrimp, 2 tbls olive oil, the lemon zest, red-pepper flakes, ½ teaspoon salt, ¼ teaspoon pepper and half the garlic. Set aside to marinate 30 minutes.
To a medium skillet, add the butter, the remaining olive oil, shallot and garlic, and heat over medium heat.
When the butter starts to bubble, add the orzo and ½ teaspoon salt and cook, stirring often, until the orzo is toasted, about 2 minutes, adjusting the heat as necessary to prevent the garlic from burning.
Add the wine and stir until absorbed, about 2 minutes.
Stir in the stock, reduce heat to low, cover, and cook until the orzo is al dente, about 12 minutes.
Stir in Parmesan and scallions.
Add the shrimp in an even layer on top of the orzo, cover, and cook until all the shrimp is pink and cooked through, 4 minutes.
Remove from heat and let sit, covered, 2 minutes.
Sprinkle with parsley and lemon juice, season to taste with salt and pepper and serve immediately
