Buttery Chocolate chip cookies
The exhaustively researched Serious Eats article `The Science of the Best Chocolate Chip Cookies' has some relevant ideas.

In particular: browning the butter beforehand (as in a buerre-noisette) brings out its nutty flavours. Since this removes moisture, it might be necessary to compensate by adding a bit more egg or egg yolk. Melting the butter gives a denser cookie that should taste more buttery than the more `cakey' cookies from the creaming method.

European butter has slightly more butter fat than American butter (minimum 82% versus minimum 80%), giving a richer taste. I suggest experimenting with several different brands.