In a food processor, blend vanilla wafers into fine crumbs. Alternatively, you can add wafers to a large ziplock bag and crush with a rolling pin. In a small bowl, mix crumbs and unsalted butter together. If needed, add more butter to hold together.
Spread cookie crumbs evenly on bottom of 6 small glasses or mini trifles. Refrigerate while preparing rest of dessert.
In a large bowl, whip cream cheese, heavy cream, sugar, and vanilla extract using a stand mixer with a fitted paddle attachment or hand mixer until smooth. Add in blackberries and mix until combined.
Spoon mixture into prepared glasses or trifles. Refrigerate for at least 30 minutes or until set. Top with additional blackberries and whipped cream, if desired.