Reserve 2 strawberries for garnish, then dice the remaining strawberries.
In a medium bowl, combine the diced strawberries and 2 tablespoons of the sugar and toss to coat. Let the strawberries macerate on the counter while you prepare the rest of the dessert.
In a large cold bowl, combine the heavy cream, vanilla and remaining 2 tablespoons sugar. Using a whisk or hand mixer, whip the cream to medium peaks. Transfer to a 1-gallon releasable plastic bag and refrigerate until ready to use.
Prepare the mousse mix according to the package instructions. Transfer to a 1-gallon resealable plastic bag.
Set aside about 1/4 cup of the crumbled chocolate wafer cookies for garnish. Fill the bottom third of each dessert cup with the remaining crumbled cookies. Cut about 1/2 inch off the bottom corner of the plastic bag filled with the mousse. Pipe the chocolate mousse into the cups, filling them about two-thirds of the way up. Top with the diced strawberries, filling up each cup to the top. Let chill about 20 minutes.
To garnish: Cut about 1/2 inch off the bottom corner of the plastic bag filled with the whipped cream and pipe onto the chocolate mousse in each dessert cup. Sprinkle with the reserved crumbled cookies. Slice the remaining 2 strawberries into quarters. Place a strawberry quarter on top of each and refrigerate until ready to serve. The desserts should be served the same day they are made.