Preheat oven to 325 degrees F (165 degrees C). Line baking sheets with foil and pinch the edges into a lip to contain drips. Grease the foil well with butter.
Place the matzos onto the baking sheets, breaking them in half if needed.
Melt the butter in a saucepan with the brown sugar over medium heat; bring to a boil and reduce heat. Simmer the mixture until thickened, about 5 minutes. Ladle the hot sugar mixture over the matzos, spreading the mixture over the matzos with a rubber spatula.
Bake in the preheated oven until the sugar mixture is bubbling and thick, about 20 minutes. Set aside to cool until the toffee coating is firm, about 15 minutes.
Place the semisweet chocolate chips into a microwave-safe bowl and microwave on Low until the chips are just melted (do not let the chocolate overheat or scorch).
Spread the melted chocolate over the toffee-coated matzos; sprinkle chopped pecans on top.
Place the baking sheets into the refrigerator until the treats are cold, about 30 minutes.
Remove the matzos from the foil, break up into pieces, and store in an airtight container or plastic bags in refrigerator or freezer.
