Preheat the oven to 400°F. In a glass bowl combine together the crushed pretzels, unsalted melted butter, and brown sugar. Press the pretzel mixture onto the bottom of a large glass baking dish. Bake for 10 minutes. Remove from oven and place on a heat-resistant surface to cool completely.
Using a handheld electric mixer whip together softened cream cheese, vanilla extract, and 2/3 cup sugar. Reserve till needed in a glass bowl.
Next using a handheld electric mixer whip together 4 tablespoons of sugar and 2 cups heavy whipping cream until stiff peaks form. Fold ONLY 1/2 of the homemade whipped cream into the cream cheese mixture and spread on the cooled pretzel crust. Refrigerate for about 40 minutes. Store the other half of the homemade whipped topping for later use.
Boil 2 cups of water in a saucepan, then add 2 (6-ounce) packages of strawberry Jello, stirring continuously until fully dissolved. Allow the Jello mixture to cool for 5 minutes, then stir in cold ice water.
Arrange the sliced fresh strawberries over the cream cheese mixture evenly.
At this time slowly pour the Strawberry Jello over the cold strawberries and cream cheese mixture. Place in the refrigerator for 2 plus hours or more to firmly set before serving.