XAML

   <Window 
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      x:Class="SDKSample.ControlTemplateButtonWindow"
      Title="Button with Control Template" Height="158" Width="290">
    
      <!-- Button using an ellipse -->
      <Button Content="Click Me!" Click="button_Click">
        <Button.Template>
          <ControlTemplate TargetType="{x:Type Button}">
            <Grid Margin="5">
              <Ellipse Stroke="DarkBlue" StrokeThickness="2">
                <Ellipse.Fill>
                  <RadialGradientBrush Center="0.3,0.2" RadiusX="0.5" RadiusY="0.5">
                    <GradientStop Color="Azure" Offset="0.1" />
                    <GradientStop Color="CornflowerBlue" Offset="1.1" />
                  </RadialGradientBrush>
                </Ellipse.Fill>
              </Ellipse>
              <ContentPresenter Name="content" HorizontalAlignment="Center" 
                VerticalAlignment="Center"/>
            </Grid>
          </ControlTemplate>
        </Button.Template>
    
      </Button>
    
    </Window>