Place a medium saucepan over medium heat, add the olive oil and heat through. Add the onion, stirring occasionally, until onions are translucent and tender, about 6 minutes.
Stir in the rice, sauté in the olive oil, stirring constantly, for 30 seconds, then add ¼ cup of the chicken stock. Reduce heat to medium-low and stir constantly until all stock has been absorbed.
Continue adding the stock ¼ cup at a time, stirring frequently, until all of the stock has been used and rice is al dente, about 20 to 25 minutes.
When the risotto is al dente remove from heat and stir in Parmesan cheese. Set aside and keep warm.
For the shrimp & scampi sauce:
Place a large sauté pan over medium heat, add the remaining olive oil and heat through. Season the shrimp on both sides with salt and pepper and arrange in the pan, working in batches if needed.
Sauté on both sides until pink and no longer translucent, about 1½ minutes per side. Remove the shrimp from the pan and set aside on a plate.
Return the pan to medium-high heat; add the garlic and stir for 30 seconds. Stir in the wine and let reduce by a third. Add the lemon juice and stir, cooking for about 5 more minutes. Remove from the heat.
Whisk in the butter one piece at a time, stirring until creamy. Stir in parsley and tarragon. Season to taste with salt and pepper.
For serving:
Ladle the risotto into warm pasta bowls then ladle scampi sauce over, dividing the shrimp evenly between the bowls.