Caramel Chocolate Crunch Bars

Ingredients:
For the base:
– 2 cups crushed pretzels
– 1/2 cup unsalted butter, melted
– 1/4 cup granulated sugar

For the caramel layer:
– 1 cup packed light brown sugar
– 1/2 cup unsalted butter
– 1/4 cup heavy cream
– 1/2 teaspoon vanilla extract

For the chocolate topping:
– 1 1/2 cups semi-sweet chocolate chips
– 1/2 cup white chocolate chips (optional for drizzle)