Pound the chicken breasts between two sheets of plastic wrap to an even thickness of about 1/2 inch. This helps them cook evenly and makes rolling easier.
Season both sides of the chicken with salt, pepper, garlic powder, and dried thyme. This builds flavor right into the meat.
Lay each chicken breast flat and create a pocket by slicing horizontally into the side without cutting all the way through. You want a Creole-style pocket that can hold filling.
Blanch or lightly steam the asparagus for 1–2 minutes until just tender but still bright green. Pat dry.
Fill each pocket with a generous line of mozzarella and a few asparagus spears. You can also add a small drizzle of olive oil to keep the filling juicy.
Secure the pockets with toothpicks if needed. This helps keep the filling inside during searing.
Heat olive oil in a large skillet over medium-high heat. Sear the stuffed chicken for 3–4 minutes per side, or until the exterior is golden and the cheese begins to melt.
Reduce heat to medium, cover the pan, and cook for another 5–7 minutes, or until the chicken reaches 165°F (74°C) internally and the mozzarella is fully melted.
Remove from heat. Squeeze fresh lemon juice over the top for a bright finish and let rest 5 minutes before slicing to serve.