Ensure butter and eggs are at room temperature for optimal mixing and a smooth batter. For faster mixing, consider using a stand mixer. If you prefer a slightly less rich option, you can try reducing the butter in the filling by a tablespoon or two without much impact on flavor. Doneness cues: The center should look mostly set, and a toothpick inserted into the center should come out with moist crumbs, not wet batter. Troubleshooting: If undercooked, bake a few more minutes; cover with foil if edges brown too fast. If dry, it’s overbaked; watch closely. Rotate pan if oven has hot spots for even baking.