Set a 6-quart Instant Pot® to high saute and add the butter (see Cook's Note). Once it has melted, add the mushrooms and cook until golden and the water has evaporated, about 6 minutes. Stir in the shallots and thyme and continue to cook until the shallots have softened, about 2 minutes. Stir in the orzo, chicken broth, lemon zest and juice. Put the chicken breasts on top of the orzo and sprinkle generously with salt and pepper.

Set to pressure cook on high for 10 minutes.

Natural release for 10 minutes, then QR for whatever steam is left.

Transfer the chicken to a cutting board with tongs and slice crosswise. Stir the spinach, cream and Parmesan into the orzo. Season with salt and pepper and serve alongside the chicken.