Halve each chicken breast lengthwise to make four thin cutlets, then season both sides with the garlic powder, lemon pepper, and salt if your lemon pepper blend has no salt.
Heat the olive oil and butter in a large skillet over medium-high heat until hot and the butter is melted.
Sear the chicken cutlets 5–6 minutes per side, until golden and cooked through (internal temperature 165°F). Transfer to a plate and tent with foil to keep warm.
Reduce heat to medium and add the minced garlic to the skillet; cook about 30 seconds until fragrant.
Pour in the chicken broth and lemon juice, scraping up any browned bits from the bottom of the pan.
Stir in the heavy cream and add the uncooked gnocchi, pushing the gnocchi so it is submerged in the liquid.
Simmer uncovered, gently bubbling, for 5–7 minutes and stir occasionally, until the gnocchi is cooked and the sauce has thickened (the gnocchi will release starch); add a splash of broth if the sauce becomes too thick.
Remove the pan from the heat, stir in the grated Parmesan and packed baby spinach until the spinach wilts and the sauce is smooth.
Return the cooked chicken and any juices to the skillet, spoon sauce over the chicken, adjust seasoning with salt and pepper, and serve immediately.