Although you mentioned that you have already found the answer to your question, I would like to offer you a detailed explanation of the difference between "¡Lo que charla tu madre!" and "¡Cuánto charla tu madre!" to enhance your understanding of the subject.

This expression is used to emphasize the quality or character of the action. In this case, it emphasizes the way your mother chats, as if it were something notable or characteristic. It doesn’t necessarily imply surprise at the quantity, but rather at the nature of the chat.

Here, the focus is on the quantity or intensity of the action. The expression "cuánto" denotes surprise, astonishment, or emphasis on the amount or frequency with which your mother chats. It's like highlighting that your mother chats a lot.

As for whether they are interchangeable, it depends on the context and what you want to express. If your intention is to highlight the quantity or frequency of the chat, "¡Cuánto charla tu madre!" would be the most suitable choice. If you want to emphasize a characteristic or notable aspect of how she chats, then "¡Lo que charla tu madre!" would be more appropriate.

Both phrases can have a similar meaning in a colloquial context, especially if used exaggeratedly or with a tone of surprise, but it's important to recognize the subtle difference in focus of each.

Feliz semana

Silvia