AppShell.xaml

<Shell.FlyoutHeaderTemplate>
    <DataTemplate>
        <yummy:PancakeView
            BackgroundGradientAngle="0"
            BackgroundGradientEndColor="{StaticResource flyoutGradientEndFaded}"
            BackgroundGradientStartColor="{StaticResource flyoutGradientStartFaded}"
            HorizontalOptions="FillAndExpand"
            IsClippedToBounds="true"
            VerticalOptions="FillAndExpand">
            <StackLayout Margin="0,10,0,0" Padding="25">
                <Label
                    Margin="0,2,0,0"
                    FontSize="26"
                    HorizontalOptions="CenterAndExpand"
                    Text="Header Title Here"
                    TextColor="White"
                    VerticalOptions="Center" />

            </StackLayout>
        </yummy:PancakeView>

    </DataTemplate>
</Shell.FlyoutHeaderTemplate>