*I'm not sure how many cups it takes for the pretzels. Arrange the pretzels in a single layer on a rimmed half sheet pan (13x18x1-inch). The pretzels should touch each other in one single layer.
Cook the butter and brown sugar in a medium saucepan (The mixture will bubble some so the sides of your pan needs to be at least 3-inches deep.) over medium-low heat until the sugar is melted and smooth. Stirring with a whisk slowly. When it begins to bubble, cook for 3 minutes while stirring.
After the 3-minutes is up, pour the mixture slowly and evenly over the pretzels. Make sure all of the pretzels are covered in the sugar mixture.
Place the toffee-covered pretzels in the oven and bake at 325°F for 15 minutes.
After 15 minutes, remove from the oven and sprinkle chocolate morsels evenly over the top. Return to the oven until the chips begin to melt and lose their shape, about 1 minute. Remove and use an offset spatula, spread the melted chocolate evenly over the surface.
Sprinkle nuts or salt over the chocolate before it hardens, if desired.
Let stand until nearly set and firm. This time will depend on the temperature and humidity. You can refrigerate to speed the process.
Break or cut into pieces. Store refrigerated in an airtight container.