Brew the coffee nice and strong, using about 2–3 tablespoons ground coffee per cup of water. Let it cool to room temperature, then chill it in the fridge until cold so it doesn’t melt the ice and water down the frappuccino.
In a medium bowl, combine the cold heavy cream, powdered sugar, and 1/2 teaspoon vanilla. Whip with a hand mixer or whisk until soft, billowy peaks form. Cover and refrigerate while you prepare the rest of the drink.
In a small bowl, mix together the crushed caramel candies or toffee bits, crushed cookies, and coarse or turbinado sugar. Adjust the ratios to taste, using more candy for sweetness or more cookie for buttery crunch. Set aside.
Warm the caramel sauce for 5–10 seconds in the microwave until pourable. Drizzle it in a spiral around the inside of two tall glasses, letting it drip down the sides. Add about 1 tablespoon of caramel to the bottom of each glass for extra caramel ribbons, if desired. Sprinkle in an extra pinch of sea salt if you like a salted caramel twist.
In a blender, combine the chilled coffee, milk, ice cubes, 1/4 cup caramel sauce, sugar or simple syrup, 1/2 teaspoon vanilla, and a pinch of fine sea salt. Blend on high until thick, smooth, and frosty. If the mixture is too thin, add a few more ice cubes and blend again. If it’s too thick to pour, add 1–2 tablespoons of milk and blend briefly.
Taste the blended frappuccino. If you prefer it sweeter, add a bit more caramel sauce or sugar and blend again. For a stronger coffee flavor, add 1 tablespoon instant coffee granules and pulse until dissolved and combined.
Pour a little of the frappuccino mixture into each caramel-drizzled glass. Spoon a small amount of caramel sauce over this layer. Repeat with more frappuccino and more caramel, building up alternating layers to create visible caramel ribbons throughout the drink.
Top each drink with a generous spoonful or piped swirl of whipped cream. Drizzle additional caramel sauce over the whipped cream, then sprinkle the crunchy caramel-cookie topping over the top so it sticks to the whipped cream.
Add a wide straw to each glass and serve right away while the drink is thick and icy and the crunchy topping is crisp.