Line a 9-inch baking dish with parchment paper or wax paper. Secure the paper to the sides of the pan with binder clips, so it doesn't slip around.
Cut the cookies into 4ths and set aside.
Over a double boiler, melt the white chocolate chips, stirring occasionally with a spatula, until smooth and melted.
Pour 1/3 of the chocolate into the pan and spread it out into an even layer. Scatter the chopped cookies over the chocolate (reserving 2 tablespoons of cookies), and press them into the chocolate.
Pour the remaining chocolate over the cookies and spread it it out as smoothly as possible. Chop the reserved two tablespoons of cookies a little more finely, and scatter them over the chocolate.
Set aside to cool completely until firm; you can place the pan in the refrigerator to speed things up, but you don't want the chocolate to be too cold and hard when you cut it.
Lift the slab of chocolate out of the pan by lifting up the paper. Peel the paper off, and place the chocolate on a cutting board. Use a sharp chef's knife to cut the chocolate into 16 squares.
Store the chocolate in a freezer bag or airtight container at room temperature (in a cool dry place) for up to 1 month, or in the freezer for 3-6 months.