Heat the butter and olive oil in a large saucepan over medium heat. Add the onions and cook, stirring often, for 3-4 minutes. Add the white wine and cook for 2 minutes, until reduced.
Add the garlic and orzo, and cook, stirring constantly, for 1-2 minutes.
Add the chicken broth, season with sea salt and freshly cracked pepper, and cook uncovered, stirring occasionally, until the broth is absorbed. Taste the orzo to make sure it's cooked through, if not, add a bit more broth and continue cooking until cooked to al dente.
Add the frozen peas and Parmesan cheese then stir until evenly combined. Allow the orzo to cook for 1-2 minutes, or until the peas are cooked and the Parmesan is melted. Taste and re-season if needed.