Prepare the Dumpling Batter
In a large bowl, combine the flour, thyme (or parsley), black pepper, and salt. If you prefer lighter dumplings, incorporate the optional baking powder and baking soda as well. Create a well in the center of the dry ingredients and pour in the whisked eggs. Stir everything together until a stiff dough forms. If the mixture seems too dry, add milk one tablespoon at a time until you achieve the right consistency - not too sticky but cohesive enough to hold its shape.
Cook the Dumplings
Bring a large pot of salted water to a rolling boil. Using a tablespoon, scoop portions of the dumpling dough and carefully drop them into the boiling water. To prevent the dough from sticking to the spoon, dip your spoon in hot water between each scoop. Allow the dumplings to cook undisturbed until they float to the surface, which indicates they're fully cooked - this typically takes 3-5 minutes. Remove them with a slotted spoon and set aside on a plate while you prepare the cabbage.
Sauté the Onions
In a large pot, melt 2 tablespoons of butter over medium heat. Add the chopped onion along with a pinch of salt and cook until the onions become soft and develop a light golden color, approximately 8-10 minutes. Stir occasionally to prevent burning and ensure even cooking.
Cook the Cabbage
Add the remaining 2 tablespoons of butter to the pot with the onions, followed by the chopped cabbage, stock, garlic powder, salt, and pepper. Stir everything thoroughly to combine, ensuring the cabbage is evenly coated with the butter and seasonings. Bring the mixture to a simmer, then cover with a lid and allow it to cook until the cabbage becomes tender but still retains some texture, about 15-20 minutes.
Combine and Serve
Once the cabbage is cooked to your liking, gently fold in the cooked dumplings, being careful not to break them. Toss everything together to combine and allow the dumplings to absorb some of the flavorful cabbage liquid. Taste and adjust the seasoning with additional salt and pepper if needed. Transfer to a serving dish, garnish with freshly chopped parsley, and serve hot.