Heat 1 tablespoon of olive oil and 1 tablespoon of butter in a large skillet over medium-high heat. Once foaming, add the gnocchi in a single layer. Cook for 2-3 minutes per side, undisturbed, until golden brown and crisp. Remove with a slotted spoon and set aside.

Season the cubed chicken with salt and pepper. Add it to the same hot skillet and cook, stirring occasionally, for 5-7 minutes until golden brown on all sides and cooked through. Remove the chicken and set it aside with the gnocchi.

Lower the heat to medium and add the remaining tablespoon of butter to the skillet. Add the minced garlic and optional red pepper flakes. Sauté for about 30 seconds until fragrant, being careful not to burn the garlic.

Pour in the chicken broth to deglaze the pan. Use a wooden spoon to scrape up any browned bits from the bottom. Bring to a simmer and let it reduce by about half.

Lower the heat and stir in the heavy cream and lemon zest. Let the sauce gently simmer for 2-3 minutes to thicken slightly.

Turn off the heat completely. Slowly stir in the freshly grated Parmesan cheese until it has melted smoothly into the sauce. Finish by stirring in the fresh lemon juice.

Return the cooked chicken and seared gnocchi to the skillet. Add the fresh spinach and gently stir everything together to coat in the sauce. The residual heat will wilt the spinach and warm everything through.

Taste and adjust seasoning with more salt and pepper if needed. Serve immediately.