Preheat oven to 350 F. In a mixing bowl, whisk together ½ cup sugar and 3 tbsp. tapioca.
Slice 2 cups of strawberries and 2 cups of rhubarb into half-inch slices. Add strawberries and rhubarb to the mixing bowl, and gently stir to coat in sugar and tapioca.
Pour into an 8″ square pyrex and bake for 25-30 minutes. Once done, gently mix once more, and refrigerate for 1 hour.
While strawberry-rhubarb cools, whip 1 cup heavy whipping cream in a blender for about 30 seconds, or until it appears to stop splashing. Add whipped cream to a clean mixing bowl.
With the whipped cream, add 12 oz. whipped cream cheese, 1½ tbsp. real vanilla extract and ½ cup condensed milk. Whip mixture on high with a hand mixer until thoroughly mixed. Refrigerate for 1 hour to set.
In a food processor, crumble 2 cups Nilla wafers (that's 2 cups, once crumbled). You want them to be a tiny bit chunky, not fine. Add them to a mixing bowl with 4 tbsp. melted, salted butter. Stir until thoroughly mixed.
Once strawberry-rhubarb is cooled and the mousse is set, layer into glasses with the crumbles. Start with crumbles, using a kitchen tool to flatten them down (I used a lemon juicer, but you can use a spoon). Then, simply layer strawberry-rhubarb, mousse, crumbles, strawberry-rhubarb then mousse.