For the Peanut Butter Sauce:

1. Combine butter and brown sugar. Place ¼ cup unsalted butter and ½ cup packed brown sugar in a medium saucepan over medium heat. Stir frequently as the butter melts and sugar dissolves, about 2-3 minutes. The mixture should be smooth and well combined.
2. Add peanut butter. Add ½ cup natural creamy peanut butter to the butter and sugar mixture. Stir continuously to combine smoothly. The heat helps the peanut butter incorporate seamlessly into the sauce base.
3. Incorporate cream. Slowly add ⅓ cup heavy cream or whole milk, stirring constantly to create a smooth, homogeneous sauce. The cream creates the luxurious texture that makes this sauce special.
4. Add vanilla and salt. Remove from heat and stir in 1 teaspoon vanilla extract and ¼ teaspoon sea salt. These final ingredients add smoothness and enhance all the other flavors.
5. Cool slightly. Let the sauce cool for about 2 minutes at room temperature. It will thicken slightly as it cools, reaching the perfect consistency for drizzling. The sauce should be warm but not scalding hot when you serve it.

For Assembling the Sundae:

6. Prepare your serving dishes. Use bowls or dishes of your choice. If possible, chill them in the freezer for 5 minutes before serving.
7. Add peanut butter ice cream. Scoop 1 generous scoop of peanut butter ice cream (or vanilla) into your prepared dish. Position it carefully in the center or slightly to one side.
8. Add chocolate ice cream. Scoop 1 generous scoop of chocolate ice cream and place it next to or on top of the peanut butter ice cream. The two ice cream flavors should complement each other visually and positionally.
9. Drizzle peanut butter sauce. Pour approximately 2 tablespoons of warm homemade peanut butter sauce over the peanut butter ice cream, allowing it to cascade down the sides and pool slightly at the bottom.
10. Drizzle chocolate sauce. Pour approximately 2 tablespoons of warm chocolate sauce or hot fudge over the chocolate ice cream, creating beautiful artistic patterns.
11. Add whipped cream crown. Place a generous dollop of whipped cream on top of the ice cream, using a spoon to create attractive peaks and swirls.
12. Sprinkle crushed peanut butter cups. Add approximately 3 tablespoons of crushed peanut butter cups over the whipped cream and onto the sauces. Crush them into varied sizes—some larger pieces for texture, some finer pieces for distribution.
13. Add optional toppings. If desired, add roasted peanuts, chocolate shavings, rainbow sprinkles, or additional crushed candy pieces for visual interest and extra flavor.
14. Serve immediately. Present your peanut butter cup sundae right away while the sauces are warm and the ice cream is cold. This temperature contrast is what makes the sundae special.