Creating Getter/Setter method within powershell class

classtest.ps1

Class FooBar {
    [string]$Prop1

    Foobar() {
        $this | Add-Member -Name Prop1 -MemberType ScriptProperty -Value {
            # This is the getter
            return $this.Prop1
        } -SecondValue {
            param($value)
            # This is the setter
            $this.Prop1 = $value
        } -Force
    }
}

$FooBar = [Foobar]::new()

This breaks if you try to access the property with someting like $FooBar.Prop1 or $FooBar.Prop1 = "This doesn't work..."