In a 13 by 9-inch pan, add the pretzels, butter, and 2 tablespoons sugar. Stir to combine. Press mixture into the bottom of the pan and bake 8 to 10 minutes. Remove from the oven and set aside to cool.
In a stand mixer or a medium bowl, add the cream cheese, 2 tablespoons sugar, powdered sugar, cocoa powder, and beat until well blended. In a clean bowl, combine 2 cups of the heavy cream, vanilla, 1 tablespoon sugar, and a pinch of salt and beat until soft peaks form. Gently fold the whipped cream into cream cheese mixture and spread it evenly over the cooled pretzel crust.
Add the pineapple juice to a small pot over medium-high heat, and bring to a simmer. Remove from the heat, add the gelatin powder and stir to dissolve. Add the strawberries and let mixture come to room temperature or quick chill it over a bowl filled with ice water while whisking. Pour the gelatin mixture over cream cheese layer and refrigerate until set, about 1 hour.
Whip the remaining 2 cups of heavy cream with remaining 2 tablespoons sugar. When the strawberry gelatin layer is set, smooth the whipped cream over the top and sprinkle evenly with chocolate shavings. Refrigerate at least 2 hours before serving.