% Fichier ex12.2.3-6.tex - Ch. Rolland/O Reilly France
\documentclass{article}
\usepackage[latin1]{inputenc}
\usepackage{fancybox}
\begin{document}
\newcommand{\Dblcadre}[1]{%
{\setlength{\fboxrule}{3pt}%
\setlength{\fboxsep}{2pt}%
\fbox{\setlength{\fboxrule}{1pt}%
\setlength{\fboxsep}{20pt}%
\fbox{\begin{Bcenter}%
#1\end{Bcenter}}}}}

\Dblcadre{\LaTeX\\par~la~pratique}
\end{document}
