1. Preheat your oven to 375°F or 190°C.

2. In a large mixing bowl, combine the ground beef, egg, salt, and black pepper. Use your hands or a wooden spoon to mix the ingredients until just combined – try not to overdo it.

3. Divide the mixture into 12 equal portions and shape each one into a ball, placing them on a plate or tray as you go.

4. Melt 1 tablespoon or 15 grams of butter in a large frying pan over medium heat, then add 6 of the meatballs. Cook until they're browned all over, which should take about 5 minutes. Remove the cooked meatballs and set them aside, then repeat with the remaining 6.

5. Add the remaining 1 tablespoon or 15 grams of butter to the same frying pan, followed by the heavy cream. Bring the mixture to a simmer and cook for 5 minutes, or until it thickens slightly. Season with salt and black pepper to taste.

6. Arrange the cooked meatballs in a single layer in a greased 9x13-inch or 23x33-centimeter baking dish. Pour the creamy sauce over the meatballs, making sure they're fully coated.

7. Transfer the baking dish to the preheated oven and bake for 20-25 minutes, or until the top is golden brown and the sauce is bubbly.

8. Remove the dish from the oven and let it cool for a few minutes before serving hot with boiled potatoes and a fresh side salad.