Preheat an oven to 180 degrees C. Line two baking trays with aluminium foil. Place the matzo crackers in a single layer on the lined baking trays, breaking to fit if necessary.
Bring the butter and brown sugar to a boil in a heavy bottomed saucepan over medium heat. Continue to cook, stirring constantly until thick and smooth, about 3 minutes. Pour the hot sugar mixture over the matzo and spread evenly with a heat proof spatula.
Place the caramel topped matzo in the preheated oven for 10 minutes. Remove from oven and evenly sprinkle the chocolate chips on top. Return pans to oven to melt chocolate, about 1 minute. Smooth melted chocolate to completely cover the caramel. Sprinkle with the chopped walnuts. Chill in refrigerator for 20 minutes or until set. Break into small pieces to serve.