How to show text inside a progressbar?

I have a question concerning wpf as I am still a beginner. I have a MetroProgressbar which works fine, I use bindings for several properties like foregroundcolor(because on certain conditions it gets changed..) and of course value. So it worked all out for me until I tried to display a text inside the progressbar, and I can't really find a solution, however I tried this so far:

<Controls:MetroProgressBar  Minimum="{Binding ProgressMin}" Maximum="{Binding ProgressMax}" BorderBrush="{Binding ProgressBarBorderBrush}" Background="White" Foreground="{Binding ProgressBarForeground}" HorizontalAlignment="Stretch" Margin="5 5 5 5" VerticalAlignment="Top" Height="30"  Value="{Binding ProgressValue}" BorderThickness="2" FlowDirection="LeftToRight">
                            <Controls:MetroProgressBar.Template>
                                <ControlTemplate TargetType="ProgressBar">
                                    <Grid >
                                        <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>
                                        <TextBlock Text="test123" Foreground="{Binding ProgressBarForeground}" FontSize="12" Margin="5 0 0 0" HorizontalAlignment="Left" VerticalAlignment="Center"/>
                                    </Grid>
                                </ControlTemplate>
                            </Controls:MetroProgressBar.Template>
                        </Controls:MetroProgressBar>

Now the only thing that works is the Textblock correctly bound to the foreground property. The progressbar does not display any value anymore, but when I set the background of the grid to a color, the progressbar still gets filled.

Any fix or better ideas? Thanks in advance.