This goes in Xaml

<Window x:Class="TestApp.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:logger="clr-namespace:LoggerControl.Views;assembly=LoggerControl"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:TestApp"
    mc:Ignorable="d"
    Title="MainWindow" Height="450" Width="800">
	<Grid>
		<logger:LogControl x:Name="LogView" />
	</Grid>
</Window>


Set the Datacontext in code behind

var logger = new Logger.Core.Logger();
LogView.DataContext = new Logger.Core.LogControlViewModel(logger);
logger.Log("Test App working");