Preheat oven to 360 degrees F (180 degrees C).
Slowly melt the Butter (50 gram) over medium heat in a large pot. When the butter is bubbly and foaming, add the Onion (1) and Celery (1 cup) and sauté until the celery has softened and the onion has started to become translucent.
In a big mixing bowl, add Breadcrumbs (5 cup), Dried Thyme (1 tablespoon), Dried Sage (1 teaspoon), Fresh Parsley (1 cup), Salt (1 teaspoon), and Freshly Ground Black Pepper (1 dash). Stir together.
To the dry ingredients, add the cooled onion mixture and Cream of Mushroom Soup (10.5 ounce) and mix together until you have a crumbly blend.
With wet hands, shape a handful of the mixture into a meatball shape.
Place all of the balls on a lightly greased baking dish with room in between each. Cover with foil and bake in the preheated oven for 25 minutes.