Beat softened cream cheese in mixer until smooth. Slowly ad heavy whipping cream 1/4 cup at a time, and beat until fluffy, like very heavy whipped cream. Add vanilla extract. Still mixing, slowly add erythritol or sugar substitute of your choice and mix until sugar substitute dissolves and is no longer grainy (taste is the best test for this). Fold in crumbs. Fill ice cream molds (These work great, or get creative with foil) and insert popsicle sticks. (If desired, sprinkle more crumbs into the bottom of the mold before filling or around the popsicle stick as decoration.) Freeze until set, at least 3 hours before serving.