Not able to write config to $HOME / root

[ScopeSV]

I'm writing a CLI which needs a config file in the $HOME directory.
I have no problems writing to a local config file "." however the file doesn't want to write in $HOME:

const FILE_NAME string = "config.toml"
const PATH string = "$HOME/.config"

func init() {
	viper.SetConfigName(FILE_NAME)
	viper.SetConfigType("toml")
	viper.AddConfigPath(PATH)

	if err := viper.ReadInConfig(); err != nil {

This gives an expected error:

Config File "config.toml" Not Found in "[/Users/stephan/.config]"

The path looks correct. So once we write the file, it should exist.

I've tried writing the file two different ways:

err := viper.WriteConfig()

Results in error:

Config File "config.toml" Not Found in "[/Users/stephan/.config]"

So it doesn't want to write to a file that doesn't yet exist.

Ive also tried:

err := viper.WriteConfigAs(FILE_NAME)

Which results in error:

open $HOME/.config: no such file or directory

(Also tried a combination of both path and file name, error is the same:)

open $HOME/.config/config.toml: no such file or directory

If I set the path to

	viper.AddConfigPath(".")

The file gets written, even though it doesn't exist initially.

What gives? How can I go about writing a config file in my $HOME?