Preheat oven to 350°F. Line a baking sheet with parchment paper.
In a medium bowl whisk together flour, cocoa powder, and baking soda until combined. Cut in butter using hands or a fork until it resembles a coarse crumb. In a separate bowl whisk together Splenda Brown Sugar Blend, milk, and vanilla until sweetener dissolves. Add milk mixture to flour mixture and mix using a hand mixer until dough comes together.
Form dough into a ball and refrigerate for 1 hour. Roll dough out on a floured surface into a ⅛” thick square. Cut into 4” x 2” rectangles using a pastry cutter or sharp knife. Lightly imprint 3 rows of dots with fork tines in each graham cracker. Arrange on prepared baking sheets, leaving ¼” space between each graham cracker. Bake until firm, about 14 to 18 minutes. Let cool for 30 minutes before using.
Fill the bottom of a 13” x 9” baking dish with a single layer of graham crackers. Spread 1 ¼ cup of whipped topping evenly over graham crackers. Repeat the process for a total of 8 layers, ending with a layer of whipped topping.
Sprinkle with chocolate shavings. Wrap the baking dish in plastic wrap and freeze until firm, about 4 hours. Slice and serve.