Preheat over to 375°.
Break apart spinach into slightly smaller pieces so it will be easier to combine with the rest of the filling. Microwave for approximately 2 minutes or until wilted, stirring halfway through. Set aside.
In a small bowl, mash together the goat cheese, butter, parsley, thyme, salt, pepper, lemon juice, garlic, dill and sun-dried tomatoes. After mixed well, add spinach and mix again until spinach is well-covered by the cheese-spinach-sundried-tomato mixture.
Divide into two equal pieces. Cut slits in chicken and stuff with mixture.
Place chicken breasts on greased baking dish. Cook in preheated oven for 35 minutes.